Peanut Butter Cup Blondies

Ingredients
1 cup (2 sticks) unsalted butter, melted, plus more, room temperature, for pan
1 cup packed light-brown sugar
1/2 cup granulated sugar
2 large eggs
1 1/2 teaspoons pure vanilla extract
2 cups all-purpose flour (spooned and leveled)
1 1/2 teaspoons coarse salt
8 Reese's peanut butter cups, removed from their wrappers and corasely chopped
Directions

1. Preheat oven to 350. Brush an 8-inch square baking pan with butter; line pan with parchment paper, leaving a 2-inch overhang on two sides. Butter paper.
2. In a large bowl, whisk together butter and sugars until smooth. Whisk in eggs and vanilla. Add flour and salt; stir just until moistened. Transfer batter to prepared pan and smooth top. Arrange chopped peanut butter cups in 12 rows on top of dough.
3. Bake until top of cake is golden brown and a toothpick inserted in center comes out clean, 45 to 50 minutes. Set pan on a wire rack and let cool completely. Using parchment overhang, lift cake from pan and transfer to a cutting board; cut into 16 squares. To store, keep in an airtight container at room temperature, up to 2 days.