Simmer cream and sugar in medium saucepan, stirring to dissolve sugar. Add chocolate; whisk until smooth. Chill until just spreadable, about 6 hours.
For almond cake:.
Preheat oven to 350°F Butter three 9-inch-diameter cake pans with 1 1/2-inch-high sides. Line bottoms with parchment paper; dust pans with flour. Whisk flour, baking powder, and salt in bowl. Using heavy-duty mixer, blend brown sugar and butter in large bowl. Beat in almond paste 1 piece at a time, then beat until smooth. Add eggs 1 at a time, beating well after each addition. Beat in extracts. Fold in dry ingredients. Divide batter among pans; smooth tops. Bake cakes until tester inserted into centers comes out clean, about 25 minutes. Cool cakes in pans on rack.
For almond praline:.
Line baking sheet with foil. Stir sugar and 1/4 cup water in heavy medium saucepan over medium-low heat until sugar dissolves. Increase heat; boil without stirring until deep amber, swirling pan and brushing down sides with wet pastry brush occasionally. Mix in nuts. Pour onto foil; cool. Peel foil off praline. Chop praline coarsely. DO AHEAD Praline can be made 1 day ahead; store airtight at room temperature.
For mascarpone frosting:.
Beat all ingredients in large bowl just to soft peaks (do not overbeat or mixture will curdle).
Run knife around pan sides to loosen cakes. Turn cakes out; peel off paper. Place 1 cake layer on platter. Spread half of ganache over; sprinkle with 1/4 cup praline. Top with second cake layer. Spread remaining ganache over; sprinkle with 1/4 cup praline. Top with third cake layer. Spread frosting over top and sides of cake. DO AHEAD Cake can be made 1 day ahead; cover with cake dome and chill. Store remaining praline airtight at room temperature.
For chocolate bark:.
Line baking sheet with foil. Melt chocolate in small bowl set over saucepan of simmering water. Stir until smooth. Remove from over water. Drizzle all but 1 tablespoon chocolate over foil in thick (about 1-inch-wide) zigzag lines (chocolate will pool in spots). Sprinkle 3 tablespoons praline over chocolate; chill bark until firm, about 1 hour.
Press praline around bottom 2 inches of cake; sprinkle more atop. Peel foil off bark; break into pieces. Press edges into frosting atop cake. Remelt 1 tablespoon chocolate over simmering water, stirring often. Using spoon, drizzle chocolate over cake. DO AHEAD Chill up to 4 hours. Serve cold or at room temperature.