Line a 9 x 5-inch loaf pan with clear plastic wrap; set aside.
Gently melt 1/2 cup butter (saving remaining 2 sticks) in a heavy saucepan set over low heat (do not allow to hiss or brown). Remove from heat. Stir in chocolate chips until melted and smooth. Stir in amaretto. Cool to room temperature.
Beat remaining 1 cup (2 sticks) butter with an electric mixer. Gradually add powdered sugar, scraping inside of bowl as you do. Add egg yolks 1 at a time, scraping bowl and beating well after each addition.
Beat in cooled chocolate mixture until completely combined. Stir in ground almonds.
In a medium bowl with clean beaters, beat the egg whites and cream of tartar. Begin on low speed, and gradually increase speed until soft, billowing peaks form. Gently fold a spoonful of egg whites into chocolate mixture, to lighten. Fold in remaining egg whites, until mixture is light, foamy and evenly combined.
(To fold, hold large rubber spatula like a knife. "Cut" through the center of mixture, reaching down to the bottom of bowl. Scrape up from bottom of bowl, and pull over the top of the mixture. Give bowl a quarter-turn and repeat. When finished, mixture will be a thick, creamy mousse - not soupy.)
Spread a layer of chocolate mousse in bottom of loaf pan; top with a layer of cookies. Repeat, ending last layer with chocolate batter. Refrigerate overnight. Invert onto plate. Slice to serve. Garnish each slice with whipped cream and additional roasted almonds.
To roast almonds: Spread almonds on a cookie sheet and bake in a 350 degree F oven until thoroughly browned, about 12 to 20 minutes. Stir occasionally to brown evenly. Grind almonds in a food processor or, in batches, in a coffee grinder.Makes 12 Source: