Double Chocolate Brownies

Makes 9 large or 16 small

6 tablespoons unsalted butter, plus more for pan
6 ounces semisweet chocolate, coarsely chopped
1/4 cup unsweetened Dutch process cocoa powder
3/4 cup all-purpose flour
1/4 teaspoon baking powder
1/4 teaspoon coarse salt
1 cup sugar
2 large eggs
2 teaspoons pure vanilla extract

1. Preheat oven to 350 degrees. Line a buttered 8-inch square baking pan with parchment, allowing a 2-inch overhang. Butter lining (not overhang).

2. Put butter, chocolate, and cocoa powder in a heatproof bowl set over a pan of simmering water; stir until butter and chocolate have melted. Let cool slightly.

3. Whisk together flour, baking powder, and salt in a bowl. Put sugar, eggs, and vanilla in the bowl of an electric mixer fitted with the whisk attachment, and mix on medium speed until pale, about 4 minutes. Add chocolate mixture; mix until combined. Reduce speed to low. Add flour mixture; mix, scraping down sides of bowl, until well combined.

4. Pour batter into prepared pan; spread evenly with spatula. Bake until a cake tester inserted into brownies (avoid center and edges) comes out with a few crumbs but is not wet, about 35 minutes. Let cool slightly in pan, about 15 minutes. Lift out; let cool completely on a wire rack before cutting into squares. Brownies can be stored in an airtight container at room temperature up to 3 days.