01 - Preheat your oven to 350°F (175°C). Thoroughly grease and flour two 9-inch round cake pans.
02 - In a large mixing bowl, whisk together the all-purpose flour, granulated sugar, baking soda, fine sea salt, and unsweetened cocoa powder until well combined.
03 - In a separate bowl, whisk together the vegetable oil, buttermilk, large eggs, red food coloring, vanilla extract, and white vinegar until the mixture is smooth.
04 - Gradually incorporate the wet ingredients into the dry ingredients, mixing until just combined. Be careful not to overmix the batter.
05 - Divide the cake batter evenly between the two prepared 9-inch round cake pans.
06 - Bake for 30 to 35 minutes, or until a toothpick inserted into the center of the cakes comes out clean.
07 - Allow the cakes to cool in their pans for 10 minutes before inverting them onto wire racks to cool completely.
08 - While the cakes are cooling, beat the softened cream cheese and softened unsalted butter together in a bowl until light and fluffy. Gradually add the sifted powdered sugar, vanilla extract, and a pinch of salt, beating until the frosting is smooth and has a spreadable consistency.
09 - Once the cakes have completely cooled, level them if necessary. Place one cake layer on your serving plate. Spread a generous amount of cream cheese frosting over the top. Place the second cake layer on top and then frost the top and sides of the entire cake.
10 - Roll the gray fondant into small oval shapes to form bodies and smaller balls for heads. Use a tiny amount of water to attach the heads to the bodies. From the pink fondant, shape tiny ears and tails and attach them. Press dark chocolate chips into the fondant to serve as eyes and noses.
11 - Arrange the fondant rats in a chaotic pattern across the frosted cake. Dust the cake lightly with cocoa powder and scatter the chocolate cookie crumbs around to create a messy "dirt" effect. Drizzle additional frosting around the cake for an extra "chaotic" visual.