Russian Korolevsky Cake (King's Cake)

Instructions

1. Cake Prep Instructions:
2. Grease and generously flour a 9" non-stick cake pan.
3. On a dry skillet, over medium-high heat, toast 1 cup of walnuts until lightly golden then chop into small pieces.
4. In the bowl of an stand mixer with a whisk attachment, beat together 2 eggs and 1 cup sugar until pale yellow (4 minutes on medium/high speed). Reduce the speed to low and add 1 cup flour. Mix until well-blended.
5. Put 1 cup sour cream in a large measuring cup. In a small ramekin, combine 1 tsp baking soda with 1 tsp vinegar. It will fizz up, then stir it right away into the sour cream.
6. The sour cream will start to visibly rise. Once you notice it rising, mix it into the cake batter using a spatula.
7. In the first cake batter, mix in 1 Tbsp cocoa. Repeat steps 1-3 but In the second cake batter, mix in 2 Tbsp poppy seeds and in the third cake batter, mix in 1/2 cup toasted, chopped walnuts.
8. Pour batter into prepared cake pan and bake at 380˚F for 20-22 minutes or until the top is golden and a toothpick comes out clean. Let cake layers cool to room temperature.
9. Frost the top of each layer (see frosting instructions below)
10. Sprinkle the top with the remaining 1/2 cup chopped walnuts
11. Using a whisk attachment, beat together on high speed the cooked sweetened condensed milk and 2 sticks of butter for 3 to 4 minutes until fluffy. Frost once the cake is cooled to room temperature.