In a large microwave safe bowl, melt the peanut butter and butter together. It'll take 2-3 minutes to melt, make sure you stir the mixture after every 45 seconds. Once completely smooth, remove from the microwave.
1 cup peanut butter, 1 cup unsalted butter
Add in the confectioners' sugar, vanilla extract and salt. Stir everything together with a rubber spatula until the mixture is very thick and smooth.
3 teaspoons vanilla extract, 3 cups confectioners' sugar, ½ teaspoon kosher salt
Pour into the 8x8 pan and use a small offset spatula to even out the top. Chill for at least 3 hours. Slice into 64 1" squares or larger squares if you prefer!
Notes
My recipes have been developed and tested in metric grams. I highly recommend using a weighing scale and measuring out your ingredients the metric way. Butter: I use European style butter, like Kerry Gold, in my recipes. This will make your finished bake much creamier and richer.Salt: If you don’t have kosher salt, halve the amount of salt called for in the recipe. 1 teaspoon kosher salt = ½ teaspoon fine salt.Peanut Butter: use a creamy commercial peanut butter and not a natural peanut butter which has oil on the top.Storage: store in an airtight container in the fridge for up to 1 week, or in the freezer for up to 3 months.