Preheat oven to 350 °F (180 °C).

In bowl, beat sugar with egg yolks. Stir in coffee and vanilla; set aside.

In other bowl combine, flour, baking powder and salt. Gradually beat dry ingredients into sugar mixture with electric mixer, until smooth.

Beat egg whites, until soft peaks form and fold in sugar mixture. Pour mixture into a 9 inch (22.5 cm) buttered springform pan. Bake for 35 minutes or until knife inserted in centre comes out clean. Remove from oven and let cool.

Remove sponge cake from pan. Cut cake in half horizontally. Spread bottom layer with Rhubarb and Strawberry Mousse and cover with top layer. Place cake back into springform pan and refrigerate for several hours. Before serving, remove cake from pan and spread with Cream Cheese Icing.

Strawberry Rhubarb Mousse:
In saucepan, combine rhubarb, sugar and water. Simmer while stirring, until rhubarb is tender. Purée mixture in blender.

Blend in strawberries, sour cream and Canadian Cream cheese, until smooth. Pour in large bowl and set aside.

In small bowl, sprinkle gelatine over 2 tbsp (30 mL) of water; allow to stand for 1 minute. Add 2 tbsp (30 mL) of boiling water, stirring constantly until gelatine completely dissolves. Stir dissolved gelatine into strawberry and rhubarb mixture.

In separate bowl, beat egg whites until stiff but not dry and gradually beat in sugar. Fold stiff egg whites into strawberry and rhubarb mixture. Set aside.

Cream Cheese Icing:
In bowl, whip all ingredients until creamy.