Preheat oven, butter pan and line bottom with parchment.

Stir chopped chocolates in top of double boiler over simmering water until melted and smooth. Cool slightly. Process macadamia nuts and flour in processor or blender until nuts are finely ground. Transfer nut mixture to small bowl.
Do not clean processor.
Add butter and sugar to processor and blend using on/off turns until mixture is smooth. Add eggs, Cognac, instant espresso (or coffee) and vanilla, process until smooth. Add melted chocolate and process until just combined. Add nut mixture and process using on/off turns until mixture is just combined. Transfer batter to prepared pan. Smooth top with spatula.
Bake until toothpick inserted halfway between edge and center of cake comes out clean.
Cool cake in pan on rack 30 minutes. Invert cake onto rack; remove parchment and cool.

FOR GLAZE:

Bring cream to a boil in heavy small saucepan. Remove from heat. Add chocolate and stir until melted and smooth. Stir in corn syrup. Let glaze stand until cool enough to spread, about 20 minutes. Transfer cake to serving plate. Spread glaze over top and sides of cake. Refrigerate until set. Let stand at room temperature 1 hour before serving.