Using the bottom of the 8x8 baking dish as a template, cut out a piece of parchment paper. This piece will be used to help smooth the peanut butter fudge and will stay in place and protect the top of the fudge while it is chilling in the refrigerator.

Measure out enough parchment paper to hang over the sides of the pan. You will use the overhanging edges to lift the fudge out of the pan.

Spray the bottom of the 8x8 baking pan with cooking spray before lining the pan with the parchment paper. This keeps the paper in place while you are spreading the fudge.

Line the 8x8 prepared pan with the parchment paper.

Add the unsalted butter and creamy peanut butter in a medium-sized microwave-safe bowl. Heat for 60-90 seconds until the butter is completely melted. Carefully remove the bowl from the microwave and stir.

Add the 2 teaspoons of vanilla extract and stir until the vanilla is incorporated.

Slowly add the sifted powdered sugar, 1 cup at a time, stirring with a large spoon in between adding the powdered sugar. The peanut butter mixture will become stiffer to stir; continue stirring until the powdered sugar is completely combined and no white streaks or lumps are visible.

Pour the fudge mixture into the prepared 8x8 baking dish. Using a spatula to help evenly distribute the fudge in the pan.

Place the pre-measured piece of parchment paper on top of the fudge. Use this to help smooth the top of the fudge. Leave this piece of parchment paper in place, and put the fudge in the refrigerator to chill for 2 hours.

Remove the fudge from the refrigerator at the end of the 2 hours. Remove the top piece of parchment paper. Using a sharp kitchen knife, pre-score the size and number of the serving pieces of fudge (4 by 4 or 6 by 6), but do not cut the fudge until you remove it from the pan.

Using the over-hang pieces of paper, lift out the fudge, and place it on a cutting board.

Warm a large sharp knife under hot water. Dry the blade and, using the pre-measured score marks, slice the pieces of fudge.

Once the pieces are cut, gently press 2-3 red and green M&M’s on the top of each piece of fudge for decoration. (Pressing too firmly can cause the fudge to crack).