Brownie Cookie Sandwiches with Cookie Dough Buttercream

Name: Brownie Cookie Sandwiches with Cookie Dough Buttercream
Prep time: 30 min
Cook time: 10 min
Total time: 40 min
Cuisine: American
Ingredients: 8 tablespoons (113 g) unsalted butter; 9 ounces bittersweet chocolate chips (or chopped chocolate); 3/4 cup plus 2 tablespoons (175 g) granulated sugar; 1/2 cup (100 g) light brown sugar, packed; 3 large eggs, room temperature; 1 tsp vanilla; 1 cup (125 g) all purpose flour, spooned and leveled; 3/4 cup (95 g) bread flour, spooned and leveled (substitute with more all-purpose if you do not have bread flour); 1/4 cup (25 g) Dutch process cocoa powder, sifted; 1 tsp baking powder; 3/4 tsp salt; 1 tsp baking soda; 12 tablespoons (170 g) unsalted butter, room temperature; 1/2 cup (100 g) brown sugar; 2 1/2 cups (300 g) confectioners sugar, sifted; 1/2 cup (65 g) all-purpose flour; 1 teaspoon vanilla; 1/4 teaspoon salt; 3-4 tablespoons heavy cream