To make easy peanut butter fudge, bring 2 cups of sugar and 1/2 cup of milk to a boil in a medium saucepan. Boil the mixture for 3 minutes, and then stir in 1 1/3 cups of smooth or crunchy peanut butter and a 7-ounce jar of marshmallow creme.
Mix the ingredients until they are completely blended, and remove the saucepan from the heat. Quickly pour the mixture into a buttered 8-inch baking dish. Refrigerate the fudge mixture until it cools completely, and then cut it into squares.
To make a rich peanut butter fudge, combine 8 ounces of unsalted butter and 1 cup of smooth peanut butter in a large microwave-safe bowl. Cover the bowl with plastic wrap, and microwave the mixture on high power for 2 minutes. Stir the mixture, and microwave it for 2 more minutes.
Stir in 1 teaspoon of vanilla extract and 1 pound of powdered sugar to the peanut butter mixture until the fudge thickens slightly and loses its sheen. Grease an 8 x 8-inch baking dish with butter and line it with a large sheet of parchment paper. Do not trim the parchment.
Spread the peanut butter mixture evenly into the dish and fold the excess parchment paper to cover the fudge. Refrigerate the fudge for 2 hours until it is completely cool, and then cut it into 1-inch pieces.