No-Bake Microwave Peanut Butter Fudge

This quick microwave peanut butter fudge shows you can make wonderfully smooth, creamy fudge in just a few minutes. With only four ingredients and around five minutes of hands-on time, this simple recipe comes together in the microwave before your coffee gets cold.

Many microwave fudge attempts end up gritty or dry, but this reliable peanut butter fudge achieves a velvety texture thanks to the use of icing (powdered) sugar, which blends seamlessly into the mixture.

What’s to love about this recipe

• Only four ingredients required for a fuss-free batch.
• Minimal hands-on time — about five minutes to prepare.
• Perfect for peanut butter lovers who want a quick sweet treat.
• Consistently reliable texture—smooth, not gritty.
• Use smooth or crunchy peanut butter depending on the texture you prefer.
• Easy to customise with mix-ins: chocolate chips, nuts or a sprinkle of sea salt.
• No candy thermometer or special equipment needed.

Key ingredient notes and substitutions

Please refer to the ingredient list in the recipe card below for exact quantities.

Peanut butter

Smooth peanut butter gives the creamiest, silkiest result. If you prefer texture, crunchy peanut butter works well and adds pleasant crunch.

Butter

Use unsalted butter to control the overall saltiness; many peanut butters already contain salt.

Vanilla extract

A teaspoon of vanilla warms and rounds the flavour of the fudge.

Icing sugar

Icing sugar (also called powdered or confectioner’s sugar) is essential for a smooth finish. It dissolves into the other ingredients, avoiding the grittiness regular granulated sugar can cause.

If you have a sieve, sift the icing sugar first to remove lumps. If not, break any clumps with a fork before combining the ingredients.

How to make peanut butter microwave fudge

1. Line a 20cm (8 inch) square tin with parchment paper, leaving an overhang to make lifting the set fudge easier.
2. Sift 450 g of icing sugar into a large bowl, or break up any lumps with a fork if you don’t have a sieve.
3. Place 230 g unsalted butter, 250 g smooth (or crunchy) peanut butter and 1 teaspoon vanilla extract in a microwave-safe bowl.
4. Microwave the butter and peanut butter mixture for about 2 minutes, stirring halfway through, until everything is melted and runny.
5. Stir the melted mixture until completely combined and smooth.
6. Pour the warm peanut butter mixture over the icing sugar.
7. Mix thoroughly, scraping the bottom and sides of the bowl. Use a pressing or “squishing” motion with a spatula to force the icing sugar into the wet mixture — this helps prevent dry pockets and ensures an even texture.
8. Continue mixing until the mixture is uniformly smooth and no dry sugar remains.
9. Spoon the fudge into the prepared tin and press it into the corners, leveling the surface with an offset spatula or the back of a spoon.
10. Cover the tin and refrigerate for at least 1 hour to firm up. Longer chilling improves slicing.
11. When set, lift the slab out using the parchment paper overhang, place on a cutting board and score guide lines across the top where you plan to slice.
12. Cut into pieces with a large, sharp knife. For small bites, score into 8 x 8 strips for 64 squares; for larger pieces, 6 x 6 gives 36 pieces.

Variations

This peanut butter fudge is delicious on its own and also adapts well to many mix-ins and toppings. Ideas to try:

• Fold in chopped peanuts, milk or white chocolate chips.
• Sprinkle chopped peanuts or sea salt on top before chilling.
• Add a melted chocolate layer on top and chill for a two-tone bar.
• Stir in crushed pretzels, chopped toffee, or swirl in a spoonful of chocolate-hazelnut spread.
• Replace peanut butter with almond or cashew butter for a different nutty profile.
• Crumble over vanilla ice cream as a crunchy topping.

Serving and gifting suggestions

• Package small squares in pretty boxes, cellophane bags or jars for holiday gifts.
• Wrap larger bars in brown paper and tie with string or ribbon for a rustic gift presentation.
• Place individual pieces in colourful cupcake liners for parties or gifting.
• Use shaped silicone moulds for themed treats at celebrations like Valentine’s Day.
• Attach a simple recipe card so recipients can recreate the fudge at home.

Storage

Keep the fudge in an airtight container to prevent drying. A rigid plastic or glass container with a tight lid is best.

Store at room temperature for up to one week or in the fridge for up to three weeks. Placing a sheet of parchment or wax paper directly on top of the fudge before sealing helps reduce air exposure.

For longer storage, freeze the fudge for up to three months. Thaw overnight in the fridge before serving.