Preheat oven to 350 F. Butter the bottom and sides of a 10-inch spring-form pan, or two 7-inch spring-form pans. Dust the bottom and sides with flour. (This really helps prevent the cake from sticking to the pan.)
Melt chocolate and butter together in a saucepan over low heat, or in the top of a double boiler. Stir until smooth. Remove from heat and cool to lukewarm. Stir in vanilla and Amaretto.
Meanwhile, beat egg yolks with brown sugar until very thick and the mixture forms a ribbon when beaters are removed. Gently fold chocolate mixture into the egg yolks.
Beat egg whites in your mixer, or in a bowl with clean and dry beaters until stiff peaks form. Gently fold the egg whites in three batches into the chocolate-egg yolk mixture. Do not over mix or beat the mixture, because you want the air to stay in the mixture.
When just blended, pour the mixture into the prepared pan(s). Bake 25-30 minutes for the 10-inch, and 20-25 minutes for the 7-inch pans, or just until the center of the cake is barely set and still a little bit jiggly. Remove from oven and cool completely. Refrigerate at least an hour, or overnight before serving.
When ready to serve, slice cake and serve with a dollop of unsweetened whipped cream (or barely sweetened with a little Amaretto or whatever liqueur you used), a drizzle of raspberry coulis, and chocolate shavings. We make our chocolate shavings by running a potato peeler over a bar of dark chocolate and it works out well, but if you have another method, that is great too!