1-Prepare the chocolate simple syrup: Begin by boiling 1/2 cup water and 1/2 cup granulated sugar until dissolved, then whisk in 1 tablespoon dark cocoa powder and let it cool.

2-Preheat and prepare pans: Preheat your oven to 350°F (175°C) and grease your cake pans with parchment lining for easy release.

3-Mix dry ingredients: In a large bowl, combine the dry ingredients: 2 cups all-purpose flour, 2 cups granulated sugar, 3/4 cup dark cocoa powder, 2 teaspoons baking powder, 1 1/2 teaspoons baking soda, and 1 teaspoon fine salt.

4-Combine wet ingredients: Mix in the wet ingredients 1 cup warm water, 1 cup sour cream, 1/2 cup oil, 2 eggs, 2 teaspoons vanilla extract, and optional 1 teaspoon instant espresso until just combined for a smooth batter.

5-Pour and bake the batter: Divide the batter evenly into your prepared pans I recommend weighing it out for uniform layers. Bake for 22-25 minutes, checking with a toothpick for moist crumbs, not dry batter. Once done, cool the cakes in the pans for 15 minutes, then move them to racks. For even better results, chill them in the freezer for 30 minutes to make leveling easier.

6-Prepare the frosting: Beat 2 cups unsalted butter until creamy, then gradually add 1 cup sifted dark baking cocoa, 1 teaspoon vanilla, 1/2 teaspoon salt, 5 cups powdered sugar, 3/4 cup heavy cream, and 1 1/3 cups melted cooled dark chocolate chips until smooth and fluffy.

7-Assemble the cake: Brush the cooled layers with the simple syrup, spread frosting between them along with optional mini chocolate chips, and freeze briefly for stability.

8-Final touches and serving: Finish by frosting the entire cake, pressing on more mini chocolate chips for decoration, and letting it set before slicing.