Preheat oven to 350 degrees. Spread the almonds on a cookie sheet and toast in the oven until golden, about 15 minutes. Set aside to cool. Turn the oven down to 275 degrees. Butter the bottom and sides (not the lip) of a 9-inch glass pie plate.

Place the egg whites in a bowl of an electric mixer and set over a pan of hot tap water until slightly warmed. Then whisk the warm egg whites until soft peaks form. Whisk in the cream of tartar and then add the granulated sugar in a slow, steady, stream, whisking continuously. Continue whisking until stiff and glossy, 15 to 20 minutes longer. Make a pie shell with the meringue by smoothing it over the bottom and sides of the buttered pie plate. Bake until slightly crisp and dry, 15 minutes. Cool on a rack.

Combine the two chocolates in a bowl over simmering water, and stir occasionally until melted. Let cool to room temperature. Combine the heavy cream, confectioners' sugar, cinnamon and vanilla in a mixing bowl. Beat at medium speed until very soft peaks form, 2 to 3 minutes. Stir one third of the cream into the melted chocolates to lighten. Then add that mixture to the whipped cream and fold in until completely incorporated. Scatter half of the toasted almonds over the cooked meringue shell. Top with the chocolate cream filling, smoothing the top. Decorate the top with the remaining toasted almonds and grated chocolate or chocolate curls, if desired. Cover and refrigerate at least one hour before serving.