Deep Chocolate Cake with Orange Icing

Name: Deep Chocolate Cake with Orange Icing
Ingredients: For the chocolate cake; 1 1/4 cups all purpose flour; 3/4 teaspoon baking soda; 3/4 teaspoon kosher salt; 1/2 cup packed light brown sugar; 1/2 cup strong coffee (or use instant espresso); 1/2 cup unsalted butter; 8 ounces bittersweet chocolate, chopped; 1/2 teaspoon vanilla extract; 2 eggs, lightly beaten; 1 cup whole milk; For the orange icing; 2 tablespoons unsalted butter, softened; 2 cups confectioners' sugar, sifted; 1 1/2 tablespoons orange zest; 1/2 teaspoon orange extract; 2 teaspoons Cointreau or other orange flavored liqueur; 1 tablespoon mascarpone; 1 tablespoon milk, plus more as needed