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

In a mixing bowl, combine ricotta cheese and sugar, and mix until smooth.

Add eggs one at a time, mixing well after each addition.

In another bowl, whisk together flour, cocoa powder, baking powder, baking soda, and salt.

Gradually add the dry ingredients to the wet mixture, mixing until just combined.

Stir in vegetable oil and vanilla extract until smooth.

Pour the batter into the prepared cake pan and smooth the top.

Bake for 35-40 minutes or until a toothpick inserted in the center comes out clean.

Allow the cake to cool in the pan for 10 minutes before transferring to a wire rack to cool completely.

Dust the cooled cake with powdered sugar and serve with fresh berries if desired.