**NOTE BEFORE BEGINNING: You’ll need to heat-treat the flour for both the cookie dough portion that will be just for topping (i.e. the portion NOT going to be baked in the cake) and the cookie dough frosting portion, as well as sift it afterwards in order to be edible. Those instructions are in the post of the cookie dough. **

1. Prep: Preheat the oven to 350F. First we’ll make the cookie dough (make 1 full batch then a separate half batch, to be saved for topping). Then we’ll make the cake batter, followed by the brownie batter. While the cake is baking, you can make another small batch of brownies (as instructed in the topping section) for topping the cake afterwards. Grease a 9×13″ baking pan with cooking oil and line with parchment paper. 
2. Make the edible cookie dough: Prepare the cookie dough according to instructions, make one full batch and dividing in half (one portion for the cake batter and the remaining half batch for the topping of the cake). Or make one half of the cookie dough with heat-treated flour (for decoration) and the other half without heat-treated flour (because it will be baked into the cake). Set aside.
3. Make the batter: In a large bowl, whisk together the melted vegan butter, dairy free yogurt, sugar, light brown sugar, vanilla extract, and sea salt. Add in the baking powder and baking soda, and whisk again. Then add in the flour along with the buttermilk, and whisk JUST until combined. Switch to a silicone spatula and pour in the chocolate chips. Fold the chocolate chips into the batter to evenly distribute throughout the batter.
4. Make the brownie batter: Make the fudge sauce by heating the neutral oil in the microwave until hot, about 1-2 30-second intervals in the microwave. Pour the hot oil over the 3 ounces of vegan chocolate in a heat-safe bowl. Let sit for 2 minutes to melt the chocolate, then stir until the chocolate is completely melted into the butter. Then add in the cocoa powder, and stir until dissolved. Set aside. Next, in a separate medium bowl, whisk or use a hand mixer to whisk together the dairy free milk, granulated sugar, brown sugar, dairy free yogurt, vanilla extract and sea salt. Mix on medium speed until the sugar is nearly dissolved. If you pinch the batter between your fingers, you should feel very small granules if at all. Pour in the chocolate fudge sauce, and mix with a hand mixer again until the chocolate mixture is combined. Then add in the flour, and mix on low speed JUST until the flour is integrated into the chocolate brownie batter.
5. Assemble the cake: Pour the cake batter into the prepared pan. Then take a large ice cream scoop and scoop dollops of batter on top of the cake batter, leaving room for large “patties” of cookie dough. Next, take the half batch portion of the cookie dough and press large scoops (roughly 3-4 tbsp) into large patties. Place each cookie dough patty onto the cake so that it alternates with the brownie batter (see blog post photo). 
6. Bake: Place the cake into the oven to bake for 45-50 minutes, or until a toothpick comes out clean. Remove from the oven and let cool for 20 minutes in the pan before transferring to a cooling rack to fully cool before frosting. 
7. While the cake is baking: You can prepare another half batch of brownie batter (as listed in the toppings section) for decorating the cake.
8. When ready to decorate: Prepare both frostings according to their separate instructions. To frost, alternate with scoops of chocolate and cookie dough frosting. Use a spoon to smear and swirl the frostings together. Top with sliced vegan brownies and cookie dough balls.
9. Slice and serve! Slice into 12-18 cake slices and enjoy! Store any leftovers in an airtight container and in the fridge for up to 5 days. Or in the freezer for up to 2 months!