Chocolate Cake:

1. Preheat oven to 350ºF with oven rack in middle position. Prep three 9” cake pans by buttering the insides, lining the bottoms with parchment rounds, and dusting the sides with cocoa powder. (Tap out excess.)
2. In the bowl of a stand mixer fitted with the paddle attachment (or using a bowl and handheld electric mixer), combine the sugar, flour, sifted cocoa powder, baking soda, and salt. Whisk together well. Add the eggs, buttermilk, slightly cooled butter, and vanilla and mix together on medium-low speed until smooth, about 2-3 minutes, stopping halfway to wipe down bottom of bowl and beater as needed. Add hot coffee and stir in with a rubber spatula just until incorporated; the batter will be VERY thin and liquidy.
3. Divide batter evenly between prepared cake pans. Bake for 35-45 minutes, just until a toothpick inserted into the center of the cake comes out clean or with only a few moist crumbs. The sides of the cake should also be pulling away from the edges of the pan when done.
4. Cool cake in pans for 15 minutes. Meanwhile, line three wire racks with large pieces of plastic wrap.
5. To transfer cake to rack, place rack upside-down over cake pan and, holding the two together, flip cake onto rack. Peel parchment off of cakes. Allow cakes to cool completely, and then wrap entirely with plastic wrap until ready to assemble. Freeze wrapped cakes for thirty minutes just before assembling.

Brown Butter Chocolate Chip Cookie Dough:

1. Place the butter in a small skillet over medium-low heat. Cook, whisking occasionally, until the butter has melted completely and starts to bubble. Continue to cook while whisking more frequently until the butter turns a rich golden-hazel color with brown specks forming on the bottom of the pan. Remove from heat immediately and transfer to a small bowl to cool in the freezer. (Make sure you use a container that can handle the temperature change, or keep at room temp to cool slightly before putting in freezer.) Freeze until firm but not rock-hard, stirring at least once while freezing.
2. Combine cooled butter and brown sugar in clean bowl of stand mixer fitted with paddle attachment. Cream together until lighter in color and consistency.
3. Add cream and vanilla extract and beat in until smooth. Add the flour and salt and fold in until completely incorporated. Fold in 3 ounces chopped chocolate until evenly dispersed.
4. Line a plate or small baking sheet with parchment paper. Pull off nine 1/2 ounce portions of cookie dough and roll each into a ball between your palms. Spread out on parchment and chill in refrigerator until firm before adding chocolate drizzle. Transfer remaining cookie dough to a bowl and cover with plastic wrap. Refrigerate while making frosting (you still want the reserved cookie dough to be soft for mixing with the frosting, so take it out of the fridge a bit before using if it gets firm).
5. For chocolate drizzle: Fit a piping bag with a coupler, with a rubber-band tied around the bag just above the coupler. Place remaining 1 ounce chopped chocolate in piping bag and place bag in a microwave-safe cup with the tip pointing down. Microwave chocolate for 30 second increments, “smushing” the chocolate together in the bag between increments, until it has melted completely. Attach a small round tip to the coupler (I used Wilton #5 ) and remove the rubber-band. Drizzle chocolate over chilled cooke dough balls. Let set.

Brown Butter Brown Sugar Frosting:

1. Place the butter in a small skillet over medium-low heat. Cook, whisking occasionally, until the butter has melted completely and starts to bubble. Continue to cook while whisking more frequently until the butter turns a rich golden-hazel color with brown specks forming on the bottom of the pan. Remove from heat immediately and transfer to a large bowl. Whisk in the brown sugar until well-incorporated. Cool in freezer until firm but not rock-hard, stirring at least once while freezing. Again, be sure that the bowl you're using can handle the rapid temperature change.
2. Combine cooled butter mixture with vanilla and salt in clean bowl of stand mixer fitted with paddle attachment. Beat on medium-high speed until very smooth. Wipe down bowl and beater and switch to whisk attachment. With mixer speed on low, gradually add the confectioner’s sugar, mixing until all is incorporated. Increase speed and beat until fluffy. Add cream cheese and beat in just until smoothly incorporated.
3. Reserve about 6 ounces/1 cup of frosting in stand mixer, transferring the remaining frosting to a large bowl.

Brown Butter Chocolate Chip Cookie Dough Filling:

1. Add reserved cookie dough to stand mixer along with reserved frosting and beat together until smooth. Use a spatula to fold in the extra 1 ounce chopped chocolate.

Assembly:

1. Place one cake layer on a cardboard cake round or plate set on a rotating cake stand (you may want to place strips of parchment under the edges of the cake to keep the bottom clean**). Spread half of the cookie dough filling over the first layer of cake. Place the second cake layer over the first and spread the remaining cookie dough filling on top.*** Top with the final cake layer.
2. Use an offset spatula to apply a thin layer of frosting to the cake over the top and sides to seal in the crumbs (this layer doesn’t need to be perfect). Transfer the cake to the refrigerator for 30 minutes to allow the crumb coat to set. If it’s a warm day, you can chill the remaining frosting during this time as well, but you may need to whip it again in the stand mixer briefly afterwards.
3. After chilling, apply a final, smooth layer of frosting all around the cake. Remove parchment strips, if you used them. Use a piping bag fitted with a closed star tip (I used Ateco #846) to pipe 9 dollops around the top perimeter of the cake. Using the same tip, pipe decoration around the base of the cake. Place a chocolate-drizzled cookie dough ball atop each piped dollop on the top of the cake.
4. Cake may be served immediately after assembling. Store any leftovers in an airtight container (I kept mine in the refrigerator) and bring back to room temperature before slicing and serving.