Preheat your oven to 350°F (175°C) and prepare a 9-inch round cake pan.

Whisk together cake flour, black cocoa powder, sea salt, and baking powder in a medium bowl.

In a large bowl, mix granulated sugar and canola oil until smooth. Add eggs, sour cream, and hot coffee, mixing just until combined.

Fold the dry ingredients into the wet mixture until just combined; small lumps are fine.

Pour the batter into the prepared pan and smooth the top. Bake for 30-35 minutes, or until a toothpick comes out clean.

Let the cake cool in the pan for about 10 minutes. Transfer to a wire rack and soak with optional espresso if desired.

In a mixing bowl, whisk together mascarpone cheese, powdered sugar, and vanilla bean paste until smooth.

In another bowl, whip the heavy cream until stiff peaks form. Gently fold into the mascarpone mixture.

Once the cake is cool, frost it with the mascarpone frosting and dust with cocoa powder if desired.

Slice and serve with fresh berries or vanilla ice cream.