Mocha Hot Fudge:

1. In a medium bowl, whisk together the cold brew, cocoa powder, chopped chocolate, and sea salt until fully combined.
2. In a heavy-bottomed saucepan, whisk together the heavy cream, granulated sugar, and corn syrup. Place over medium-high heat and stir off and on just until the mixtures comes to a full boil (look for large bubbles all across the surface). As soon as this happens, remove from heat and pour into the coffee mixture. Let sit for 1 minute.
3. After a minute, whisk the mixture for at least two minutes, until it’s glossy and smooth. Transfer to a small glass jar, cover, and transfer to the refrigerator to cool completely before using.

Coffee-Infused Chocolate Cake:

1. Preheat oven to 350ºF with rack in center position. Butter two 8” round cake pans and line with parchment circles.
2. In a medium bowl, whisk together the flour, cocoa powder, espresso powder, baking powder, baking soda, and salt.
3. In the bowl of a stand mixer fitted with the paddle attachment, beat the sugar, eggs, and vanilla extract together on medium speed for about 3 minutes, until light & fluffy. Reduce speed to low and add sour cream, beating in until combined. While beating on low speed, slowly pour in avocado oil, beating until fully incorporated. Once combined, slowly pour in cold brew and continue to beat just until incorporated.
4. Scrape down the bowl and beater. With mixer on low, slowly pour in dry mixture and continue to mix just until fully incorporated, being careful not to overmix.
5. Divide the batter evenly between the two prepared pans and bake in preheated oven for 30-35 minutes, just until a toothpick inserted into the center comes out clean or with only a few moist crumbs.
6. Cool cake in pans on a wire rack for about 30 minutes, and then turn out onto rack to cool completely before frosting.

Sweetened Condensed Milk Frosting:

1. In the bowl of a stand mixer fitted with the paddle attachment, beat together the butter, vanilla, and salt on medium speed until soft and fluffy. With mixer on low speed, slowly add the confectioner’s sugar. Once all has been added, gradually increase speed to medium and continue to beat for another 2-3 minutes, until light and fluffy.
2. Reduce speed back to low and add sweetened condensed milk. Increase speed to medium once again and beat another 2-3 minutes, until light and fluffy. Use immediately.

Assembling and Frosting:

1. Place one cake layer on a cardboard cake round set on top of a rotating cake stand. Use an offset spatula or palette knife to spread an even layer of frosting over the top. Top with second cake layer (I like to put it on upside-down) and cover entire cake with a thin layer of frosting just to seal in crumbs. Place in the refrigerator to chill for 30 minutes.
2. Set aside 1/3 cup of frosting for making the fudge frosting. Use the remaining plain frosting to frost the cake in a smooth, even layer (the top surface should be fairly smooth but doesn’t need to be perfect at this point). Transfer back to the refrigerator to chill while prepping the fudge frosting.
3. Divide the reserved 1/3 cup frosting between two bowls. Add about 1 1/2 teaspoons of fudge sauce to one bowl and stir in until fully incorporated. Add about 1 1/2 tablespoons of fudge to the second bowl and mix in fully, making sure it’s noticeably darker in color than the first batch. Place about 2 tablespoons of the coffee fudge in a third bowl.
4. Remove the cake from the fridge. Using an offset spatula, add a small dollop (about 1 teaspoon) of each frosting to the perimeter of the cake, alternating colors and working your way around the entire cake to border it.
5. Using the offset spatula, carefully swipe across each dollop in a diagonal motion down the side of the cake, stopping about halfway down. Smooth any remaining dollops on the top of the cake, rotating the cake stand as you do so to create a swirly pattern. Be careful not to overwork the frosting and lose the distinction between the different colors.
6. Serve immediately. For any leftovers, chill the cake until the frosting is firm and then carefully cover with plastic wrap.