Ricotta Chocolate Cake

1. Preheat oven at 350°F (180°C).
2. In a mixing bowl, work together the ricotta and the sugar.
3. Add the eggs, one at a time, mixing lightly.
4. At this point add the sifted flour and baking powder and mix together.
5. Add the vanilla, butter and chocolate at the end and fold to combine.
6. Pour the mixture into a greased 9-inch (23 cm) pan and level the top.
7. Put it in the oven on the middle rack and bake for about 30 minutes, or until a toothpick inserted in the middle comes out clean.
8. Take it out of the oven and let it cool on a rack.