Sprinkle the inside of each dish with 1 1/2 tsp sugar, rolling dish to coat.
Stir chocolate and butter in a heavy medium saucepan over low heat until smooth. Remove from heat.
Using electric mixer, beat egg, egg yolks, and remaining 5 tablespoons sugar on medium-high heat 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 among dishes (scant 1/2 cup batter each).
(Up to this point: can be made 1 day ahead. If doing so, cover with plastic; chill. Bring to room temperature before continuing.)
Preheat oven to 425 degrees.
Place dishes on baking sheet. Bake cakes uncovered until edges are puffed and slightly cracked, but center 1" of each one moves slightly when dishes are shaken gently, about 13 minutes.
Top each cake with a scoop of coffee ice cream and serve immediately.
