Bittersweet Chocolate Cupcakes

Preheat oven to 375°F. Lightly butter eighteen 1/3-cup muffin cups. Stir 16 ounces chopped bittersweet chocolate in top of double boiler set over simmering water until melted and smooth. Cool slightly. Using electric mixer, beat eggs, egg yolks and sugar in large bowl until pale yellow and tripled in volume, about 5 minutes. Add melted chocolate and beat until blended. Divide cupcake batter equally among prepared muffin cups, filling cups about 3/4 full.

Bake cupcakes until puffed and cracked on top, about 12 minutes. Cool to room temperature. Run knife around sides of muffin cups to loosen cupcakes, then carefully lift out with small metal spatula. Place chocolate cupcakes upside down on work surface.

Bring whipping cream to simmer in small saucepan. Remove from heat. Add remaining 8 ounces chopped chocolate and unsalted butter; whisk until melted and smooth. Cool until slightly thickened and spreadable. Spread glaze over cakes. (Can be prepared 8 hours ahead. Store in airtight container at room temperature.) Serve cupcakes glaze side up.