Prepare the Caramel: In a heavy-bottom saucepan, combine 1 cup of granulated sugar over medium heat, stirring occasionally until it melts and turns a deep amber color, about 10 minutes. Remove from heat and carefully whisk in 5 tablespoons of unsalted butter until melted, followed by ½ cup of room-temperature heavy cream. Continue stirring until the mixture is smooth, then set aside to cool slightly.

Add Salt and Vanilla: Once the caramel has cooled for about 10 minutes, stir in 1 teaspoon of sea salt and 1 teaspoon of pure vanilla extract. Allow the caramel to cool completely, then transfer it to the refrigerator to chill for at least 30 minutes.

Preheat Oven: Preheat your oven to 350°F (175°C) and prepare a 9-inch springform pan by lightly greasing it with butter or cooking spray.

Mix Dry Ingredients: In a large mixing bowl, sift together 1 cup of all-purpose flour, 1 cup of granulated sugar, ½ cup of natural cocoa powder, 1 teaspoon of baking soda, ½ teaspoon of baking powder, and ½ teaspoon of kosher salt. Whisk until well combined.

Combine Wet Ingredients: In a separate bowl, whisk together 1 large egg, ¼ cup of vegetable oil, ¼ cup of sour cream, ¼ cup of whole milk, and 1 teaspoon of vanilla extract until smooth.

Incorporate Coffee: Slowly add ½ cup of hot coffee to the wet ingredients, mixing well until the batter is fully integrated and smooth.

Bake Cake: Pour the batter into the prepared springform pan. Bake for 25-28 minutes, or until a toothpick inserted in the center comes out clean. Allow the cake to cool in the pan for about 10 minutes before transferring it to a wire rack to cool completely.

Make Caramel Mousse: In a mixing bowl, beat 1 cup of heavy cream with 1 teaspoon of vanilla extract until stiff peaks form, about 3-4 minutes.

Blend Cream Cheese and Caramel: In another bowl, beat 1 cup of softened cream cheese with ½ cup of the chilled salted caramel sauce until smooth. Fold in the whipped cream until fully incorporated.

Assemble Cake: Take your cooled cake and carefully spread the caramel mousse over the top. Cover and refrigerate for about 6 hours.

Final Touch: Once the mousse is set, remove the cake from the refrigerator. Drizzle the remaining ⅓ cup of salted caramel sauce over the top.

Serve and Enjoy: Carefully slice the cake and serve chilled, either on its own or with a scoop of vanilla ice cream.