8 tablespoons (1 stick) unsalted butter, cut into 1/2-inch cubes
9 ounces of semisweet chocolate, finely chopped
3 ounces unsweetened chocolate, finely chopped
1/2 cup (2.5 ounces) all-purpose flour
1/2 teaspoon baking powder
1/4 teaspoon kosher salt
3 tablespoons malted milk powder
3 large eggs, room temperature
1 1/4 cups granulated sugar
2 teaspoons vanilla extract
12 ounces semisweet chocolate chips