Step 1Heat the oven to 325 degrees. Butter a 9-inch springform pan.
Step 2Grind the wafers in a food processor or blender until the crumbs are very fine. Combine the butter with the crumbs and pat onto the bottom and up 1 inch of the sides of the pan. Bake 10 minutes. Remove from the oven and cool completely.
Step 1Combine the egg yolks, 1 1/2 cups sugar, vanilla, salt and brandy in the top of a double boiler set over, but not touching, simmering water. Beat until pale yellow and thickened, about 8 to 10 minutes. Remove from the water and set aside.
Step 2Melt both chocolates in the top of the double boiler, then remove from the heat and whisk in the butter, a little at a time. Gradually whisk the chocolate into the yolk mixture until smooth. The chocolate mixture will congeal and become very stiff. Stir in the coffee.
Step 3Beat the egg whites in the bowl of an electric mixer until soft peaks form. Gradually beat in the 3 tablespoons of sugar to form stiff peaks.
Step 4Fold 1 cup of the beaten egg whites into the chocolate mixture until combined, then carefully fold in the remaining beaten egg whites until thoroughly incorporated. In the same mixing bowl, whip the cream until stiff and gently fold into the chocolate mixture.
Step 5Pour the mousse into the crust and chill overnight in the refrigerator. Garnish with the cherry cordials before serving. To make slicing the cake easier, place in the freezer for 30 minutes.
Step 1Place the cherries and the brandy in a small bowl and set in the freezer.
Step 2Meanwhile, melt the chocolate in a double boiler set over, but not touching, simmering water.
Step 3When the cherries are firm, about 30 minutes, pat dry with paper towels. Dip them, one at time, into the chocolate, swirling each around by the stem until completely covered. The chocolate will harden almost immediately. Place the cherries on a wax paper-lined tray and refrigerate until ready to use.