Start by preparing the caramel sauce, as it needs time to cool and thicken before being used to fill and drizzle over the cake. While making caramel may seem daunting, it’s surprisingly simple!

Heat a saucepan over medium heat. Once the pan is warm, gradually add 1 1/3 cups of granulated sugar, about 1/4 cup at a time. Allow the sugar to melt mostly before adding the next portion. As it melts, the sugar will deepen in color. Avoid stirring excessively and let the heat do the work. If you notice the sugar starting to burn, remove the pan from the heat and reduce the heat slightly.

Continue stirring as needed until all the sugar is dissolved and the mixture turns a deep amber color. Turn off the heat.

Gradually mix in 1/2 cup of butter, 2 tablespoons at a time. Stir until fully incorporated after each addition. Then, slowly mix in 1/3 cup of heavy cream and 1/2 teaspoon of salt. The caramel will be thin initially but will thicken as it cools.

Transfer the caramel to a separate container and set it aside to cool completely.

Prepare the chocolate cake batter next.

Preheat your oven to 325°F (162°C). Line a 9x13-inch baking pan with parchment paper and spray it with nonstick spray.

Place two flower nails flat side down in the center of the pan, spaced a few inches apart. Spray them thoroughly with nonstick spray as well.

In a large mixing bowl, whisk together 3 cups of all-purpose flour, 2 3/4 cups of granulated sugar, 1/2 cup of cocoa powder, 1 1/2 teaspoons of baking powder, 1 tablespoon of baking soda, and 1/2 teaspoon of salt. Set aside.

In another large bowl, combine 1 1/2 cups of hot water and 1 tablespoon of instant coffee or espresso powder. You can substitute with 1 1/2 cups of strong, hot brewed coffee.

To the coffee mixture, add 1 cup of buttermilk, 3/4 cup of vegetable oil, 1/2 cup of sour cream, 3 large eggs, and 1 teaspoon of vanilla extract. Whisk until smooth.

Gradually add half of the dry ingredients to the wet ingredients, whisking until just combined. Then, add the remaining dry ingredients and whisk again until fully incorporated.

Pour the batter into the prepared pan, ensuring the flower nails are evenly spaced.

Bake the cake for 50-55 minutes, or until a toothpick inserted in the center comes out with a few moist crumbs. Rotate the pan halfway through for even baking. If you don’t have flower nails, bake the cake for an additional 5-10 minutes.

Let the cake cool completely in the pan on a wire rack.

Fluffy Caramel Buttercream Frosting

Beat 1 cup of softened butter on medium speed with a whisk attachment for 2 minutes, until light and fluffy.

Add 1 teaspoon of vanilla extract and 1/4 teaspoon of salt, mixing on low speed until combined.

Gradually add 4 cups of powdered sugar on low speed, adding 1/4 cup of heavy cream halfway through to make mixing easier.

Mix in 1/3 cup of the cooled caramel sauce on low speed until incorporated. Then, increase to medium-high speed and beat for an additional minute, until the frosting is super fluffy.

Cover the frosting with plastic wrap and set aside.

Once the cake has cooled completely:

Carefully flip the cake onto a wire rack and remove the flower nails.

Use a straw, chopstick, or the end of a spoon to poke holes approximately 1 1/2 inches apart across the top of the cake.

Warm the caramel sauce in the microwave in 15-second intervals until thin and pourable. Pour most of the caramel sauce over the cake, reserving about 1/3 cup for decoration. Use an offset spatula or the back of a spoon to spread the caramel across the cake and into the holes.

Spread an even layer of caramel buttercream over the cake, creating swirls with an offset spatula or the back of a spoon.

Drizzle the remaining caramel sauce over the frosting. Sprinkle with chocolate pearls and flaky sea salt for a decorative finish.

To serve, use a warm, sharp knife to cut the cake into 24 squares. Enjoy!