Set the ricotta to drain in a drive for at least one hour prior to mixing.
Preheat the oven to 350° F. Grease a 9-inch springform pan using butter or cooking spray and line the bottom with parchment paper.
In a medium bowl, mix the flour with the cocoa powder, salt and baking powder. Set aside.
In a stand mixer (insert link), cream the ricotta and sugar together until white and fluffy, about 4 minutes. This step is very important.
Mix in the eggs, one at a time, scraping down the sides of the bowl between each egg addition. Add the espresso and the oil and combine well.
Add the flour and cocoa mixture and turn the mixer on low. Mix until just combined, scraping the sides of the bowl to make sure everything is incorporated.
Pour the batter into the prepared springform pan and bake for 35-40 minutes, or until the cake tests done with a toothpick.
Transfer to a wire wrack and let cool in the pan for about 15-20 minutes before removing. Finish cooling completely on a wire rack.
Generously dust with powdered sugar, if desired and serve.