Preheat the oven to 350°F (175°C) and prepare your baking pans by greasing them lightly.

Create caramel by combining water and granulated sugar in a saucepan. Cook over medium heat until it turns golden brown, then remove from heat. Stir in unsalted butter, heavy whipping cream, salt, and vanilla extract. Set aside to cool slightly.

Mix dry ingredients in a mixing bowl by combining all-purpose flour, cornstarch, baking powder, baking soda, and salt.

Whisk wet ingredients in another bowl: combine whole milk, vinegar, unsalted butter, vegetable oil, dark brown sugar, granulated sugar, eggs, and vanilla extract until blended.

Combine mixtures by gradually adding dry ingredients to wet ingredients. Mix gently until just combined.

Fold in espresso by incorporating strongly brewed coffee into your batter.

Pour batter into your prepared pans and bake for 25-30 minutes or until a toothpick inserted comes out clean.

Cool cakes in the pans for about 10 minutes, then transfer to a wire rack. Soak with prepared caramel sauce.

Whip frosting by beating heavy whipping cream with powdered sugar and vanilla extract until fluffy.

Frost cooled cakes generously with whipped cream mixture.

Top with granulated sugar and caramelize using a kitchen torch until golden and crunchy.