Rich Chocolate Cake with Truffle Filling

Heat the milk. Coarsely chop 100 grams (approximately 3 1/2 ounces) chocolate. Add to the milk and stir until melted. Let cool down. Beat butter and sugar until fluffy. Beat in eggs, one at a time, alternating with 50 grams (approximately 1 3/4 ounces) cornstarch. Mix remaining cornstarch, flour, cocoa and baking powder. Stir in alternating with the chocolate milk.

Spoon batter into a greased 26 cm (approximately 10-inch) diameter springform pan and smooth the top. Bake in preheated 175°C (approximately 350°F) oven for 1 hour. Cover loosely with foil during the last 15 minutes. Cool cake in the pan.

For the filling, bring cream to a simmer in a pan and remove from heat. Coarsely chop 400 grams (approximately 14 ounces) chocolate and stir into the hot cream until melted. Pour into 2 large bowls and let stand for 2 hours to cool. Cut the cake crosswise into 3 even layers. Sprinkle each layer with the rum.

Beat the chocolate mixtures about 1 minute until creamy. Place the bottom cake layer on a cake layer. Spread with 1/3 of the cream in 1 of the bowls. Repeat layers with remaining 2 cake layers and cream in bowl. Spread sides of cake with cream from second bowl. Refrigerate 1 hour.