Chocolate Triangle Cake

In heatproof bowl, pour 2/3 cup (150 mL) boiling water over chocolate and cocoa powder; whisk until smooth. Set aside.

In separate bowl, beat butter with sugar until light and fluffy. Beat in eggs, 1 at a time, beating well after each addition. Beat in vanilla and chocolate mixture.

In separate bowl, whisk together flour, baking powder and baking soda. Stir into butter mixture alternately with milk, making 3 additions of flour and two of milk.

Spread evenly into 17- x 11-inch (45 x 29 cm) parchment paper-lined jelly roll pan. Bake in centre of 375°F (190°C) oven for 30 minutes or until centre of cake springs back when lightly touched. Let cool completely in pan on rack. Invert onto rack; remove pan and paper.

With long serrated knife, trim off 1/4 inch (5 mm) from edges. Cut cake crosswise into 4 even pieces.

Icing: In bowl over saucepan of hot (not boiling) water, melt chocolate; let cool. In separate bowl, beat butter until fluffy; beat in cream and vanilla. Beat in icing sugar, 1 cup (250 mL) at a time. Beat in chocolate until fluffy and smooth.

Filling: With palette knife, spread top of 1 piece of cake with 1 tbsp (15 mL) of the jam. Spread top of second piece with 1/2 cup (125 mL) of the icing; using long metal spatula, sandwich pieces together with icing over jam. Spread top of sandwiched layers with 1 tbsp (15 mL) of the jam. Spread third piece with 1/2 cup (125 mL) of the icing; stack, icing side down, onto sandwiched layers. Spread top of sandwiched layers with 1 tbsp (15 mL) of the jam. Spread top of fourth piece with 1/2 cup (125 mL) of the icing; stack, icing side down, onto sandwiched layers. Cover and refrigerate cake and remaining icing for 12 hours or until cake is firm. (Make ahead: Refrigerate for up to 24 hours.)

Let icing stand at room temperature for 1 hour or until softened; beat until fluffy. On board, stand cake up on short end. Cut diagonally from corner to corner down whole length of cake. Lay triangles on board with plain cake sides perpendicular to board. Spread 1 cake side with remaining jam and other cake side with 1/2 cup (125 mL) of the icing.

Using long, wide metal spatula, transfer triangles to serving plate, sandwiching spread sides together to make 1 large triangle. Slip waxed paper strips under edges. Spread remaining icing over triangle; refrigerate for 1 hour or until set.

Glaze: In small saucepan, bring cream and corn syrup just to boil; remove from heat. Whisk in chocolate until smooth. Transfer to bowl; let stand for 20 minutes or until slightly thickened. Pour over cake, drizzling down sides, or spread. Refrigerate for 30 minutes or until set. Remove waxed paper strips. (Make-ahead: Cover with plastic wrap and refrigerate for up to 2 days.) Let cake stand at room temperature for 30 minutes before serving.

Source : © CanadianLiving.com