Step 1

Adjust the oven rack to the lower middle position and preheat oven to 325°F (163°C).

Step 2

In a food processor or blender, pulse the sugar until fine and powdery. Remove 1 cup and set aside to use in step 3; keep the rest inside the food processor. Add the flour and salt to the food processor. Pulse 5-10 times until aerated and light.

Step 3

Using a handheld or stand mixer fitted with a whisk attachment, beat egg whites and cream of tartar together on medium low until foamy, about 1 minute. Switch to medium-high and slowly add the 1 cup of sugar.  Whip until soft peaks form, about 5-6 minutes (see photo above for visual). Add the vanilla and beat just until combined.

Step 4

Sift the flour mixture into the egg white mixture. Sift slowly in 3 additions, while gently folding it in with a rubber spatula. Then, very gently fold in the sprinkles. Scrape mixture into a 10-inch angel food cake pan. (Don’t grease the pan!)

Step 5

Bake the cake until a toothpick inserted comes out clean, about 40-46 minutes. Make sure you rotate the pan halfway through baking. Cool the cake completely upside-down set on a wire rack, about 3 hours. Once cooled, run a thin knife around the edges and gently tap the pan on the counter until the cake releases.

Step 6

Place chopped chocolate into a large bowl. Heat the cream in a small saucepan over medium heat, stirring occasionally. Once it begins to boil, immediately remove from heat then pour over the chocolate. Stir gently and slowly using a wooden spoon until the ganache is smooth. Allow it to cool for 15 minutes. During this time, it will slowly thicken. Then pour or spoon over the cake. Top with sprinkles and hazelnuts. There will likely be leftover ganache. It’s great over ice cream!

Step 7

Cover leftover cake and keep at room temperature for up to 3 days or in the refrigerator for up to 1 week.