Melt milk chocolate.
Whip heavy cream to soft peaks.
Mix egg yolks with sugar.
Soften gelatin sheets in cold water.
Mix gelatin with both the Kahlua and coffee. Set bowl over hot water bath to dissolve the gelatin.
Fold 1/3 of whipped cream into the chocolate.
Add the yolks, then the gelatin mixture.
Fold in the rest of the cream.
Pour mousse in a half-sphere silicone mold almost to the top.
Place sponge circle (1/4" thick yellow cake cut in a circle) on top. Leave in the freezer to set.
Once hard, un-mold and place in glazing racks.
Make white chocolate ganache and chocolate ganache.
Put chocolate ganache in a pastry bag. Ladle white chocolate ganache to cover each dome and pipe a stripe design of chocolate ganache over the dome.
Refrigerate to allow the glaze to set.
Decorate the bottom edge with coffee crunch.
Place a chocolate covered coffee bean on the center of each dome.