For best results, use a dark baking chocolate with high cocoa butter content (about 30 percent), such as Valrhona or Callebaut.
Generously butter eight 3/4-cup soufflé dishes or custard cups. Sprinkle inside of each dish with 1 1/2 teaspoons sugar.
Stir chocolate and butter in heavy medium saucepan over low heat until smooth. Remove from heat. Using electric mixer, beat eggs, egg yolks, and remaining 5 tablespoons sugar in large bowl until thick and pale yellow, about 8 minutes. Fold 1/3 of warm chocolate mixture into egg mixture, then fold in remaining chocolate. Fold in flour. Divide batter among soufflé dishes. (Can be made 1 day ahead. Cover with plastic; chill. Bring to room temperature before continuing.)
Preheat oven to 425°F. Place soufflé dishes on baking sheet. Bake cakes uncovered until edges are puffed and slightly cracked but center 1 inch of each moves slightly when dishes are shaken gently, about 13 minutes.
Top each cake with scoop of coffee ice cream and serve immediately.