Tan Square Caramel Slice Recipe: Gooey Homemade Bars

New Zealand is celebrated for so many things: breathtaking landscapes, The Lord of the Rings filming locations, the world-famous All Blacks rugby team, and rich Māori traditions including the powerful haka. But tucked into everyday Kiwi baking is a humble favourite known as Tan Square, sometimes called Tan Slice.

This dessert is delightfully straightforward and is built from three simple components:

1. A crumbly, buttery shortbread base.
2. A smooth, rich caramel layer.
3. A scattering of shortbread crumbs on top for extra crunch.

If you know old-fashioned jam crumble bars, the technique is similar and the result is equally satisfying: a crisp shortbread, a lush condensed milk caramel, and a textured crumb topping. The version below uses a dark brown sugar caramel for depth, though you can choose lighter sugar for a milder flavour.

This recipe is ideal for afternoon tea, lunchboxes, or as a thoughtful homemade gift in a pretty tin. It’s approachable for novice bakers and forgiving in many respects if you follow the basic steps for the shortbread base and caramel.

Fast facts – New Zealand

What’s to love about this recipe

• Using dark brown sugar gives the caramel a deeper, more complex flavour; light brown sugar produces a milder result.
• The shortbread base is partially baked before adding the caramel so it stays light and crumbly rather than dense.
• Simple technique suitable for bakers of all skill levels.
• Excellent for lunch boxes, afternoon tea, or gift tins.

Key ingredient notes and substitutions

See the recipe card below for exact quantities.

Unsalted butter

Unsalted butter is recommended so you can control salt levels. If you use salted butter, omit the ½ teaspoon of salt in the shortbread and reduce the salt in the caramel to ½ teaspoon.

Sugars

This recipe uses granulated sugar in the shortbread base and dark brown sugar in the caramel. Dark brown sugar gives the caramel a richer taste; swap for light brown if you want a lighter flavour.

Vanilla

A little vanilla rounds out the caramel and enhances the buttery notes. Pure vanilla extract is ideal, but vanilla essence also works.

Condensed milk

Use one full can of sweetened condensed milk (around 397–400 g). Small variations in weight won’t affect the result.

Golden syrup

Golden syrup is common in many supermarkets. If you can’t find it, some cooks use dark corn syrup as a substitute, though results may differ slightly.

Coarse sea salt (optional)

A sprinkling of flaky sea salt, like Maldon, brightens the caramel and balances sweetness. It’s optional but recommended—add a little, taste a square, and adjust as you like.

The baking dish

This recipe is written for a 23cm x 33cm (9″ x 13″) baking pan. If your pan is smaller, the slices will be thicker; avoid using a larger pan unless you scale the recipe up, or the bars will be too thin.

An important note on the shortbread biscuit dough

The aim is a light, crumbly shortbread. The dough will look very dry and crumb-like after combining the dry ingredients—that’s normal. Press it gently with your hands to bring it together. To keep the base light rather than dense, the recipe partially bakes the shortbread for about 15 minutes before adding the hot caramel.

How to make Tan Square: Step-by-step guide

Making the biscuit base

1. Preheat the oven to 180°C / 350°F.
2. Line a 23cm x 33cm (9″ x 13″) baking pan with parchment paper, leaving a little overhang to help lift the slice later. Lightly grease the pan before laying the paper to help it stick.
3. In a large bowl or the bowl of a stand mixer, add 250 g softened unsalted butter, 130 g granulated sugar and 1 teaspoon vanilla. Beat for at least 5 minutes until light and fluffy.
4. Fold in 400 g all-purpose flour, 2 teaspoons baking powder and ½ teaspoon salt. Beat on low-medium until the mixture resembles fine crumbs.
5. Use your hands to press the crumbs together into a uniform dough. Reserve about 220 g of this dough in a small bowl for the crumb topping.
6. Break the remaining dough into rough chunks and spread them evenly across the base of the lined pan. Press to create an even layer, using a spatula or the base of a glass to flatten.
7. Prick the base all over with a fork and bake for about 15 minutes, until it is a very light golden colour.

Making the caramel

1. While the shortbread base bakes, combine one 397 g can condensed milk, 100 g unsalted butter, 100 g dark brown sugar and 50 g golden syrup in a small saucepan.
2. Warm gently over low heat, stirring until the butter melts and the mixture comes to a slow, gentle boil. Stir constantly to prevent scorching.
3. Once it reaches a slow boil, continue cooking for about 5 minutes on low while stirring. The mixture should thicken slightly and darken in colour.
4. Remove from the heat and stir in 1 teaspoon vanilla and 1 teaspoon salt (or ½ teaspoon if you used salted butter). The caramel should coat the back of a spoon and form a ribbon that disappears within 2–3 seconds.
5. Quickly pour the hot caramel over the partially baked shortbread base and tilt the pan to spread it evenly.
6. Crumble the reserved shortbread dough over the caramel, leaving some gaps so the caramel shows through.
7. Return to the oven and bake for an additional 20 minutes, until the caramel is a deep golden brown and the crumb topping has lightly coloured.
8. Allow the tray to cool completely, then lift the bake from the pan and slice into squares. If you like, sprinkle with flaky sea salt before serving.

Top tips

Use softened butter for the biscuit base

Softened butter blends smoothly with sugar and traps air when beaten, giving a lighter crumb. Beat for at least 5 minutes.

Use full-cream condensed milk

Full-cream condensed milk yields a creamier, richer caramel. It improves texture and mouthfeel.

Warm golden syrup if cold

If golden syrup is stiff in cold weather, warm it briefly to make measuring and pouring easier.

Bring the dough together by hand

Though the shortbread crumbs look dry, pressing them gently with your hands will bind them without overworking the dough.

Pot size matters

A wider pan increases surface area and can speed up the caramel cooking time, so monitor consistency carefully.

Test the caramel

Remove the caramel from heat to check it. It will firm up slightly during baking; err on the side of slightly undercooked rather than overcooked to avoid a hard toffee consistency.

Pour the caramel immediately

Hot caramel spreads more evenly—don’t wait or it may begin to set and won’t level well.

Easier slicing

Heat a knife in hot water, dry it, then slice for cleaner edges. Wipe the blade between cuts to keep slices neat.

Variations

• Stir dark chocolate chips into the caramel before adding crumbs for a chocolate-caramel version.
• Add chopped pecans or walnuts to the topping for crunch and flavour.
• Fold desiccated coconut into the crumb mixture for a coconut caramel slice.

Storage suggestions

Store tan squares in an airtight container lined with parchment or wax paper at room temperature away from heat and direct sunlight. Properly stored, they last up to a week. To keep them longer, freeze the squares for up to three months and thaw at room temperature when ready to enjoy.

Recipe

Tan Square – An Easy Caramel Slice Recipe

Course: Dessert, Snack

Servings: 24 squares

Total time: 50 mins

Equipment

• 1 23cm x 33cm (9″ x 13″) baking tin

Ingredients

For the shortbread base / crumble topping

• 250 g unsalted butter, softened (if using salted butter, omit the ½ tsp salt)
• 130 g granulated sugar
• 1 tsp vanilla extract
• 400 g all-purpose flour
• 2 tsp baking powder
• ½ tsp salt

For the caramel layer

• One 397 g can sweetened condensed milk (approx. 397–400 g)
• 100 g unsalted butter
• 100 g dark brown sugar (or light brown sugar for a lighter caramel)
• 50 g golden syrup
• 1 tsp salt (reduce to ½ tsp if using salted butter)
• 1 tsp vanilla extract
• Flaky sea salt to sprinkle, optional

Instructions

To make the shortbread base

1. Preheat the oven to 180°C / 350°F.
2. Line a 23cm x 33cm baking pan with parchment paper, leaving an overhang for easy removal. Lightly grease the pan first so the paper adheres.
3. Beat the softened butter, granulated sugar and vanilla together for at least 5 minutes until pale and fluffy.
4. Add the flour, baking powder and salt. Beat on low-medium until the mixture resembles fine crumbs.
5. Press the crumbs together with your hands into a dough, reserving about 220 g for the topping.
6. Spread the remaining dough in rough chunks across the pan and press to form an even layer. Prick all over with a fork.
7. Bake for 15 minutes until just turning a very light golden colour.

To make the caramel layer

1. Place the condensed milk, butter, brown sugar and golden syrup in a small saucepan. Warm over low heat, stirring until the butter melts and the mixture begins a slow simmer.
2. Maintain a gentle boil and cook for about 5 minutes, stirring constantly until it thickens slightly and darkens.
3. Remove from heat and stir in the salt and vanilla. Check consistency by drizzling a little over the surface; it should leave a trail that disappears in 2–3 seconds.
4. Pour the hot caramel over the partially baked base and tilt the pan to coat evenly.
5. Crumble the reserved shortbread over the caramel, leaving some caramel visible.
6. Bake for another 20 minutes until the caramel is a rich golden brown and the topping is lightly browned.
7. Cool completely, lift from the pan using the parchment overhang, slice into squares and, if desired, sprinkle with flaky sea salt.

Notes

Use softened butter for a lighter base. Full-cream condensed milk gives a richer caramel. Warm golden syrup if it’s stiff. The caramel will firm up in the oven, so avoid overcooking on the stove. For neat slices, warm and dry a knife between cuts.