1. Prepare the Raspberry Sauce:
- In a saucepan over medium heat, combine the frozen raspberries, water, sugar, and cornstarch. Stir continuously until the mixture boils and thickens, approximately 5 minutes.
- Remove from heat and strain through a fine-mesh sieve to remove seeds. Set the sauce aside to cool.
2. Prepare the Cake:
- Preheat your oven to 300°F (150°C).
- Sift the cake flour with â…” cup of the granulated sugar onto a piece of waxed or parchment paper three times.
- In a large mixing bowl, beat the egg whites with the salt and cream of tartar until foamy.
- Gradually add the remaining granulated sugar, about 1 tablespoon at a time, beating continuously until stiff peaks form.
- Gently fold in the vanilla extract.
- Sift about ¼ cup of the flour mixture over the beaten egg whites and fold in gently. Repeat until all the flour mixture is incorporated.
- Pour the batter into an ungreased 10-inch tube pan. Smooth the top with a spatula.
- Bake for 50 to 60 minutes, or until the cake is golden brown and springs back when lightly pressed.
- Immediately invert the pan onto a funnel or bottle and let the cake cool completely upside down.
3. Prepare the Whipped Cream:
- In a large mixing bowl, beat the heavy cream with the powdered sugar and vanilla extract until soft peaks form.
- Gently fold in the fresh raspberries.
4. Assemble the Cake:
- Once the cake has cooled, run a knife around the edges to loosen it from the pan and remove it.
- Place the cake on a serving platter.
- Drizzle the raspberry sauce over the top of the cake, allowing it to drip down the sides.
- Serve slices of the cake with a dollop of raspberry whipped cream.