Sponge Cake (Makes 4 8" Round Layers)
6 eggs , separated into whites and yolks
2 cups white sugar
1/2 cup boiling water
2 tsp vanilla
2 cups sifted cake flour for best results (White flour will do in a pinch.)
3 teaspoons baking powder
1/2 tsp salt
1/2 tsp cream of tartar
1 cup of brewed espresso
OPTIONAL: 1/2 cup dark rum (or to taste - can be made without it for non-alcoholic option)
3-4 Tbsp white sugar (to taste)
Mascarpone Frosting (in order to get a fluffy frosting, make sure all ingredients are at the same temperature!)
20 oz . (~550g.) mascarpone, room temperature
2 cups icing sugar
1/2 cup heavy cream , room temperature
pinch of salt
2 tsp vanilla
Sponge Cake (Please be warned that sponge cake can be finicky, so if making this for special company, I suggest you test it out first!)
Preheat oven to 350°.
In a mixing bowl, beat egg yolks for 1 minute at medium speed.
Continuing to mix, pour in sugar, then beat for another 3 minutes.
Slowly mix in boiling water and vanilla.
In a separate bowl, sift together flour, baking powder and salt, and then slowly add to the liquid mixture at a low speed.
In a clean mixing bowl with a whisk attachment, whip your egg whites and cream of tartar until it forms stiff peaks.
Fold your egg whites into the rest of the batter gently with a spatula.
Line your cake pans with parchment paper for an easy clean-up, and spread the batter evenly between the pans.
Bake for 25-30 mins, or until a toothpick comes out clean and it springs back to the touch.
Let cool on a wire rack.
In a small pot on the stove, mix your espresso, rum and sugar, stirring until you can't feel any sugar granules left.
Slowly bring it to a boil, and then let it simmer. The longer you leave it, the thicker it will be. This part is personal preference, but I would let it go no longer than 20 mins. Usually I can only wait 5!
Set aside to cool.
In a bowl, mix mascarpone, icing sugar, heavy cream, salt and vanilla, scraping the sides occasionally.
Turn the speed up to medium-high and let it mix for another 2 minutes. You want it to be nice and fluffy and light so it doesn't stick too much to the sponge cake. If it is too stiff or hard, you may need to add a little more cream.
*Note* I have recently done some troubleshooting on the frosting as some people who have tried this recipe found that it separated and was lumpy. The key is in the temperature of the ingredients, which should all be the same in order for the fats and liquids to emulsify and create the beautifully fluffy frosting I was getting in my own kitchen. If it seems to be separating, pop it in the fridge for 20 minutes or so, and give it another go!
With a spoon, gently soak the top of each cake layer with the rum/espresso reduction. Add as much as you want, but leave a ring unsoaked around the outside so that the cake keeps some structural integrity. It's usually about 6-10 teaspoons per layer. You will probably have some reduction left over.
Plop some of the frosting between each layer, and spread out from the centre.
Repeat for each layer, and then frost the outside.
You can eat it immediately, or I highly recommend you let it sit in the fridge for the night before serving it so all the flavours can meld together!
Add some cocoa powder on the top for the real tiramisu experience!