Citrus Cheesecake with Buttercream and Lemon Curd...this calls for a celebration

My sister Sylvia is a master at a number of things, cheesecake making being one of them. Here is a celebratory cheesecake recipe if I ever saw one. It combines the citrus flavours of lemon, lime and orange.

Cheesecake Ingredients:

• 2, 250 gram blocks of Philadelphia cream cheese
• 500 g ricotta cheese
• 1 cup granulated sugar
• 4 eggs, separated into yolks and whites
• 1 teaspoon pure lemon extract
• 1 tablespoon lemon juice
• 1 teaspoon grated orange zest
• 1/2 cup full fat Greek-style lemon yogurt .

Crust Ingredients:

• 1/2 cup melted butter
• 1/4 cup brown sugar
• 2 cups graham cracker crumbs

Buttercream Ingredients:

• 1/2 cup butter
• 2 cups icing sugar
• 1/2 Tsp lemon extract
• 1//4 tsp lime powder (called True Lime, and available in grocery stores)

Final Topping Ingredient:

• a jar of lemon curd

Methods: 

Preheat your oven to 300 degrees F. 

Combine the crust ingredients and pat them into the bottom of a 12 inch springform pan. 

Beat the egg whites to form stiff peaks. Set aside.

Beat together the cream cheese, ricotta and sugar. Add the egg yolks, citrus and yogurt and mix well. Fold in the egg whites. Pour over the crust in the springform pan. Bake for 1 hour. 

When cool, top the cheesecake with a layer of the citrus buttercream. Carefully spread 1/2 cup of lemon curd over the buttercream. Chill. Slice into 8 large or 12 more moderate pieces. Sylvia suggests that you can serve the cheesecake with a dollop of whipped cream if desired. 

My gallbladder has started aching.

Perfectly baked prior to 'icing'