Place 1 teaspoon of filling on the sheet of pasta. Move along the sheet, continuing to add a teaspoon of filling about 3 fingers apart.
Use a small bowl of water and a pastry brush to paint lines of water along the pasta sheet in between the filling. This will help the dough layers stick to each other.
Place a second sheet of pasta on top of the first sheet. Use your fingers to press down around the filling to remove any air pockets. Press the top sheet to the bottom. If you have a zigzag pasta wheel use it to cut ravioli squares. Use a fork to press down the edges of the ravioli.
Bring a large pot of salted water to a boil. Boil the ravioli in small batches. They will only cook roughly 3 minutes, until they become more pale in color.
Meanwhile, heat the butter in a deep skillet. Add the remaining mint leaves (saving a few leaves for the garnish) and a few tablespoons of lemon juice.
Use a slotted spoon to remove the ravioli from the boiling water and place directly in the skillet. Stir into the lemony melted butter. Add some of the salted pasta water to create a sauce.
Continue boiling batches of ravioli and adding them to the skillet. When you have cooked all of the ravioli, taste the sauce for lemon and salt. You may add more pasta water for consistency.
To serve, grate a generous amount of parmesan on top. Arrange a few mint leaves.