Chocolate Cake:
2 cups all-purpose flour
2 1/2 cups sugar
3/4 cup Dutch-processed cocoa powder (I used Hershey’s Special Dark)
2 tsp. baking soda
1 tsp. salt
1 cup vegetable oil
1 cup sour cream
1 1/2 cups water
2 tbsp. vanilla extract
2 eggs

Chocolate-Chip Cookie Dough Frosting:
1 1/2 cups (340 g) unsalted butter, softened to room temperature
2 cups + 2 tbps. (430 g) light brown sugar
4 tsp. vanilla extract
1 1/2 tsp. salt
12 tbsp. whole milk
3 cups (270 g) mini chocolate chips (use your judgement)

Chocolate Ganache:
1/2 cup heavy cream
4 oz. semi-sweet chocolate, chopped
2 tsp. corn syrup
1/2 tsp. vanilla extract

DIRECTIONS:

1. For the cookies, part I: Whisk together flour, baking soda, cornstarch, and salt in a large bowl and set aside.
2. In a separate, medium bowl, whisk the melted butter, brown sugar, and granulated sugar together until there are no lumps. Add the egg and the egg yolk, followed by the vanilla.
3. Pour the wet ingredients into the dry ingredients, and mix together.
4. Fold in the chocolate chips, then cover and chill for at least two hours or overnight (I did overnight due to timing).
5. For the cake: Preheat oven to 350 degrees. Butter and flour two 9″ cake pans, line with parchment/wax paper, then butter and flour the parchment/wax paper.
6. Whisk flour, sugar, cocoa powder, baking soda, and salt in a large bowl.
7. Add sour cream and vegetable oil, using a spatula to blend.
8. Gradually beat in the water, 1/2 cup at a time.
9. Blend in vinegar and and vanilla.
10. Add eggs and beat until well blended.
11. Divide the batter between the two cake pans. Bake for 45-50 minutes or until cake tester comes out clean. Let cool for 20 minutes, then carefully invert onto a wire rack lined with parchment/wax paper (cakes are very soft and moist). Carefully remove parchment/wax paper from bottoms of cakes.
12. Once completely cooled, tightly wrap cakes in plastic wrap and refrigerate for at least 30 minutes or overnight to firm the cakes before frosting.
13. For the cookies, part II: Preheat oven to 325 degrees (or lower temperature to 350 degrees). Line two baking sheets with parchment paper.
14. Roll the dough into ~3 tbsp. balls (taller rather than wider) and place on the baking sheets, making sure to leave enough room (3″ or so).
15. Bake for 10-15 minutes depending on the size of the cookie dough balls (the cookies will continue to cook after taken out of the oven; the longer in the oven, the harder the cookie).
16. Allow to cool completely, then store. Set aside 3-4 cookies (there will be many more) for the cake topping.
17. For the frosting: Using a stand mixer, cream the butter and sugar at medium speed.
18. Add vanilla and beat well. Stir in flour and salt until doughy, then beat in milk until fluffy.
19. Fold in chocolate chips, then frost the cakes.
20. For the ganache: Heat the heavy cream and chocolate in a small saucepan over low-to-medium heat until smooth.
21. Stir in the corn syrup and vanilla.
22. Remove saucepan from heat and allow ganache to come to room temperature. Pour ganache over the top of the cake, and spread it to the edge, allowing it to spillover the sides.
23. For the cookies, part III: Crumble the chocolate-chip cookies that were set aside, and scatter on top of the ganache.