Simple Birthday Cake with Marshmallow Frosting

Ingredients:

Chocolate chip sponge cake

• 10 tbsp butter, plus extra for greasing pans
• 1/2 teaspoon of baking soda
• 1 teaspoon coarse salt
• 1.5 tsp baking powder
• 2.5 cups premium flour
• 2 eggs
• 1.3 cups granulated sugar
• 2 tsp vanilla extract
• 2 cups sour cream
• 1.5 cups coarsely chopped semisweet chocolate
• Special equipment: 2 round cake pans (20 cm in diameter and 5 cm in height), a kitchen thermometer

Marshmallow glaze

• 5 tablespoons cold water, plus water for the double boiler
• 1/4 tsp cream of tartar
• 1.3 cups granulated sugar
• 2 egg whites at room temperature
• 1 tbsp corn syrup
• 1 tsp vanilla extract

Preparation:

1. Preheat the oven to 350°F (175°C). Generously butter the bottom and sides of 2 baking pans. Line the bottom of each pan with a circle of parchment paper and grease with butter. Place the pans on a baking sheet.
2. Sponge cake.
   
   Melt 10 tablespoons of butter in a small saucepan over low heat. Remove the pan from the stove and let the butter cool slightly. Set aside.
   
   In a medium bowl, sift together the baking soda, salt, baking powder and flour.
   
   In a large bowl, beat the eggs, add the sugar, vanilla, and sour cream, and mix until smooth. Add the flour mixture a little at a time to the egg-sour cream mixture, whisking to avoid lumps.
3. Make a well in the center of the whipped batter and pour in the melted butter. Beat until smooth. Then, gradually fold in the chopped chocolate.
   
   Divide the dough between the two pans and smooth it out. Tap the sides of the pan lightly to even out the dough.
4. Place the baking sheet on the middle rack of the oven and bake until a toothpick inserted into the center comes out clean, 40 to 45 minutes. Remove the cakes from the oven and let them cool briefly. Invert the cakes from the pans onto a wire rack placed on the baking sheet and remove the parchment paper. Let them cool for at least 45 minutes before frosting.
5. Glaze.
   
   Pour a small amount of water, about 5 cm deep, into a saucepan to create a homemade double boiler. Place it on the stove and bring the water to a gentle simmer. Submerge the thermometer in the boiling water to remove any debris and check its functionality.
   
   In a clean, large bowl, combine 5 tablespoons of cold water, cream of tartar, sugar, egg whites, and corn syrup. Carefully place the bowl over simmering water. Turn off the heat. Using a hand mixer, whisk the egg whites while holding the bowl over the water. Do not leave the egg whites unattended or stop whisking.
6. After about 3 minutes, remove the bowl from the heat, put the mixer down, and quickly measure the temperature of the egg whites. The temperature should reach 60°C (140°F). If the temperature drops below this level, immediately return the bowl to the double boiler and continue whisking until set, about 2-3 minutes more.
7. Remove the bowl from the double boiler and stir in the vanilla extract. The mixture should be as fluffy as a marshmallow. Set the icing aside and let it cool. Cover the cake with icing, as my dad used to say, "splattering" it over the top and sides. Serve immediately.