Preheat oven to 350
Butter and flour a springform pan.
Mince the lemon zest very fine
Strain the ricotta to remove excess liquid.
Beat eggs with sugar and salt in a large bowl.
Add ricotta and beat. Slowly add the flour and baking powder. Beat some more.
Add remaining ingredients and beat till smooth. Pour into the springform, and bake for about 40 minutes; cake will have a lightly golden color.
Let cool, and then loosen the sides by running a knife or pastry spatula around the sides. Release the side and remove.