Preheat oven to 350°F (175°C) and grease a 9-inch springform pan.
In a large bowl, whisk ricotta until smooth. Add sugar and mix until combined.
Add eggs one at a time, mixing well after each addition.
Stir in melted butter, vanilla extract, and lemon zest.
In a separate bowl, whisk together flour, baking powder, and salt.
Fold dry ingredients into the wet mixture gently until just combined.
Pour batter into prepared pan and smooth the top.
Bake for 45 to 55 minutes until the center is set and a toothpick comes out with a few moist crumbs.
Cool in the pan, then remove and let cool completely before slicing.
Dust with powdered sugar before serving if desired.