Place 12 (2 3/4-inch round, 1 1/2-inch tall) steel individual cake rings on a parchment lined sheet pan. (Alternatively, you can use 1 large 9-inch round, 2 1/2-inch tall metal dessert ring.)
Cut 12 circles from the chocolate butter sheet cake and put 1 in the bottom of each metal ring. Using a pastry brush, moisten each cake with Raspberry Simple Syrup. Arrange 3 or 4 fresh raspberries inside the rings on top of the cake circles.
Melt the chocolate and 7 ounces of the butter in the top of a double boiler, over gently boiling water; upper pan should not touch water. Remove from the double boiler but keep the mixture warm and liquid.
Whip the cream until it comes to soft peaks that hold their shape. Refrigerate until needed.
Whisk the remaining 2 ounces of butter with the eggs, sugar, and raspberry liqueur in a medium bowl. Place over gently boiling water; the bowl should not touch water. Cook, whisking constantly, for 5 to 10 minutes, until the mixture reaches 160 degrees F on a thermometer. Immediately remove from the heat and with an electric mixer, whip at high speed for about 5 minutes, until cool to touch.
Whisk the egg mixture into the melted chocolate and butter. Fold in the whipped cream, mixing until no streaks of white remain.
Using a pastry bag or a large spoon, fill the prepared metal rings with the chocolate mousse, covering the raspberries. With a flat knife, smooth the mousse to make it level with tops of the rings. Cover and refrigerate at least 8 hours, until firm.
To remove from mold, warm the sides of the rings by wrapping briefly with a hot towel, or use propane torch to heat sides so they release. Wrap a chocolate band around each torte, if desired. You can also decorate by arranging fresh raspberries, chocolate truffles, chocolate shards, or chocolate leaves on top.
Preheat oven to 325 degrees F.
Brush the sides of a 12 by16-inch sheet pan with melted butter, and dust lightly with flour, or spray with cooking spray. Line the bottom with a rectangle of parchment or waxed paper.
Cream the butter in a bowl, using an electric mixer until it is very light and aerated. Add the egg yolks, a few at a time, stopping to scrape the bowl in between additions. Add the melted chocolate, scraping the bowl again, beating until the chocolate is incorporated.
Whip the egg whites and cream of tartar in a clean bowl, using an electric mixer. When they are frothy, gradually add the sugar, whipping until soft peaks form. Fold the whites into the yolk mixture.
Sift the flour onto the batter and gently fold it in. Spread evenly into the prepared pan. Bake 10 to 15 minutes, until the cake is just set and a light crust has formed on the top. Cool.
Heat the sugar and water in a small saucepan, gently swirling the pan until the sugar dissolves. Cook just until the syrup is clear: do not boil. Stir in raspberry sauce and the liqueur, if using.
In a blender or a food processor, puree the raspberries with the sugar, lemon juice and liqueur. Strain through a fine sieve to remove the seeds. Refrigerate.
This recipe was provided by a chef, restaurant or culinary professional. It has not been tested for home use.