1-First Step: Gather and prepare your pan Start by measuring out all four ingredients so they are ready to go. Grease an 8-inch or 9-inch pan, or line it with parchment paper for easy removal. An 8×8-inch pan works well for thicker pieces, while a 9-inch pan gives you slightly thinner squares. Having the pan ready before you mix the fudge is important because the mixture thickens fast. Once the sugar goes in, you want to move quickly so the fudge presses evenly into the pan.

2-Second Step: Melt the base ingredients Microwave method: Combine 1 cup butter, 1 cup creamy peanut butter, and 1 teaspoon vanilla in a glass microwave-safe bowl. Microwave on high for 90 seconds. Stir well until the mixture looks smooth and creamy. If needed, stir a little longer until there are no lumps left. Stovetop method: Combine 1 cup butter, 1 cup creamy peanut butter, and 1 teaspoon vanilla in a medium saucepan over medium-low heat. Stir constantly until everything melts into a smooth mixture. This usually takes about 5 minutes. Keep the heat gentle so the mixture does not separate.

3-Third Step: Add the powdered sugar slowly Once the base mixture is smooth, begin adding 3 1/2 cups powdered sugar a cup at a time. Stir thoroughly after each addition. This step is where the fudge gets its structure, so do not rush it. The mixture should become thick, firm, and slightly crumbly as you stir. That texture is exactly what you want. If it still feels too soft or loose, keep mixing until the sugar is fully absorbed. The fudge should look thick enough to press into the pan, not pour like batter.

4-Fourth Step: Press the mixture into the pan Spoon the fudge mixture into your prepared 8-inch or 9-inch pan. Use the back of a spoon, a spatula, or even clean hands lightly greased with a little butter to press it down evenly. Try to smooth the top as much as possible so the finished squares look neat. If the mixture sticks a bit, that is normal. The best texture is firm and slightly crumbly when pressed. That helps the pieces hold their shape after chilling.

5-Fifth Step: Chill until firm Place the pan in the refrigerator and chill for at least 4 hours. If you have time, overnight chilling gives the cleanest slices and the best texture. Do not cut it too soon, or the squares may be too soft. This resting time is what turns the warm mixture into proper fudge. It also makes the flavor settle in and gives the fudge that classic dense bite people love.

6-Final Step: Slice and serve Once the fudge is firm, lift it from the pan if you used parchment paper. Cut it into 1-inch squares for easy sharing. A small sharp knife works best, especially if you wipe it clean between cuts. Serve the pieces right away, or store them in an airtight container in the refrigerator. This recipe makes about 48 1-inch squares, which makes it great for parties, gift boxes, bake sales, or family snacking.