In a bowl, stir together ricotta, Parmesan, flour and egg yolks, ensuring all the flour is incorporated, and form into a ball.
Turn out onto lightly floured surface, and divide into quarters. Working with 1 quarter at a time and with floured hands, roll dough into a rope that’s about ¾ inch (2 cm) thick; cut into pieces that are ¾ inch (2 cm) long. Set aside on floured baking sheet.
In large pot of boiling salted water, cook gnocchi, in batches, until floating and no longer doughy in centre, about 2 to 3 minutes. Using slotted spoon, transfer to oiled tray to prevent sticking, and cover.