- Cooking spray
- 1/2 cup granulated sugar
- 1/2 cup packed dark brown sugar
- 3/4 cup water
- 1 tablespoon instant espresso or 2 tablespoons instant coffee granules
- 2/3 cup Dutch process or unsweetened cocoa
- 1/4 teaspoon salt
- 2 ounces semisweet chocolate, chopped
- 2 ounces unsweetened chocolate, chopped
- 2 tablespoons Kahlúa (coffee-flavored liqueur)
- 3 large egg yolks
- 1/3 cup sifted cake flour (such as Swan's Down)
- 6 large egg whites (at room temperature)
- 1/4 teaspoon cream of tartar
- 1/3 cup granulated sugar
- 1 tablespoon powdered sugar
- 1/4 cup raspberries (optional)
- Chocolate curls (optional)
- Preheat oven to 300°.
- Coat bottom of a 9-inch springform pan with cooking spray. Set aside.
- Combine 1/2 cup granulated sugar, 1/2 cup brown sugar, water, and espresso in a large saucepan; stir well and bring to a boil. Remove from heat; add cocoa, salt, and chocolates, stirring with a whisk until chocolate melts. Stir in Kahlúa and egg yolks. Stir in flour; cool to room temperature. Set aside.
- Beat egg whites and cream of tartar at high speed of a mixer until foamy. Add 1/3 cup granulated sugar, 1 tablespoon at a time, beating until stiff peaks form. Gently fold one-fourth of egg white mixture into chocolate mixture; repeat procedure with remaining egg white mixture, one-fourth at a time. Spoon into prepared pan. Bake at 300° for 1 hour or until a wooden pick inserted in center comes out almost clean. Cool completely on wire rack. Remove sides from pan; sift powdered sugar over cake. Garnish with raspberries and chocolate curls, if desired.
- Note: A substitution of 1/4 cup all-purpose flour may be used in place of 1/3 cup cake flour.
Cake flour is a fine-textured, soft wheat flour with a high starch content, and usually comes in a box rather than a bag. It can be found with the cake mixes at the supermarket.