- 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
- 1/4 cup each orange, yellow, and brown candy-coated chocolates (from a 12.6-ounce bag)
- Preheat oven to 350 degrees. Brush an 8-inch square baking pan with butter; line pan with parchment paper, leaving a 2-inch overhang on two sides. Butter paper.
- 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 candies in 12 rows (2 rows per color, repeating once) on top of dough.
- 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.