For the Chocolate Cake:

• 2 cups granulated sugar
• 1 cup light brown sugar, packed
• 2 and 3/4 cups all-purpose flour
• 1 and 1/2 cups unsweetened cocoa powder, sifted
• 3 teaspoons baking soda
• 1 and 1/2 teaspoons baking powder
• 1 and 1/4 teaspoons salt
• 3 large eggs + 2 large egg yolks, at room temperature
• 1 and 1/2 cups full-fat sour cream
• 1/3 cup whole milk
• 3/4 cup vegetable oil (or melted coconut oil)
• 2 tablespoons vanilla extract
• 1 and 1/2 cups hot water

For the Salted Caramel Chocolate Frosting:

• 2 cups unsalted butter (4 sticks, 16 ounces), very soft
• 4 and 1/2 cups confectioners’ sugar, sifted
• 3/4 cup unsweetened cocoa powder, sifted
• 1 teaspoon vanilla extract
• 1/2 teaspoon salt
• 3 tablespoons heavy cream (add more if needed)
• 2 tablespoons salted caramel sauce

Garnish:

• 1 and 1/4 cups salted caramel sauce
• Flaky sea salt