Design Eat Repeat

1 Preheat oven to 350℉.
2 In a large mixing bowl, add softened unsalted butter [adjustable](½ cup, i.e. 1 stick)[/adjustable], light brown sugar [adjustable](½ cup) and granulated sugar (¼ cup)[/adjustable] and beat for 2 minutes until light and creamy.
9 Mix in egg [adjustable](1 large) and vanilla extract (2 teaspoons)[/adjustable] until combined. Mix in creamy peanut butter (½ cup).
4 Mix in baking soda [adjustable](½ teaspoon), baking powder (½ teaspoon), and salt (½ teaspoon)[/adjustable].
10 Add all-purpose flour [adjustable](1 ¼ cups)[/adjustable] and mix until all the flour disappears into the dough.
5 Let dough sit for 5 minutes to firm up a little. If dough still seems too sticky to form, place in the refrigerator for 5-10 minutes.
6 Line a baking sheet with parchment paper. Scoop dough into 3-tablespoon-sized scoops.
11 Roll dough into balls, then flatten. Add a Reeses cup to the center, then fold the dough over top the Reese cup to cover it. Roll it back into a smooth, slightly flat disc. Place on the parchment-lined baking tray and gently flatten the dough. 
7 Bake at 350℉ for 9-10 minutes, or until edges are lightly golden brown. For soft cookies, it's best to take them out before the edges are brown. They will look slightly underbaked but will continue to firm up as they cool.
8 Remove from oven and place entire pan on a cooling rack. Once cooled, drizzle with chocolate if desired.