Prepare an 8x8 baking dish. If it is NOT a non-stick dish, cover it with a light layer of non-stick cooking spray.
Put the powdered sugar, cocoa powder, milk and butter pieces in a microwave safe bowl.
Microwave the ingredients for 2 to 4 minutes, checking on it every so often. Once the butter is melted well, remove the bowl from the microwave, add in the vanilla extract and stir it all together until smooth.
Put the mixture in your prepared pan.
Chill it in the refrigerator for about an hour or in the freezer for about 15 minutes until set and firm.
You can vary the recipe after it has melted in the microwave before adding the vanilla extract by using a few different ingredients.
For mint chocolate fudge, omit the vanilla extract and use 1 teaspoon of mint extract. (Mint is a stronger flavor than vanilla, so it only needs half the amount.)
For brownie batter fudge, add in 1 tablespoon of chocolate syrup in addition to the vanilla.
For cherry cordial fudge, add 1/2 teaspoon almond extract, 3/4 teaspoon vanilla and 2 teaspoons of cherry juice. (We use juice from a jar of maraschino cherries.)
For toffee bar chocolate fudge, mix the fudge as described and then top liberally with toffee bits.