Preheat the oven to 350 degrees F.
Grease a 9 X 5-inch loaf pan with butter.
In a small bowl, whisk together flour, baking powder, kosher salt, and lemon zest.
In an electric mixer fitted with a paddle attachment, cream together butter, ricotta cheese, and sugar until light and fluffy, about 3 minutes.
Add eggs one at a time, mixing well after each addition.
Mix in vanilla extract and lemon juice.
Gradually add the flour mixture, beating until just blended.
Pour the batter into the prepared pan and bake for 45-50 minutes, or until a toothpick inserted into the center comes out clean.
Allow the cake to cool in the pan on a wire rack for 10 minutes, then turn out onto the rack to cool completely.
Optionally, dust the top with confectioners’ sugar.