In a fine-mesh strainer, strain the ricotta while preparing the remaining ingredients.
In a non-stick skillet over medium heat, cook the spinach in the butter for about 1 minute or until just wilted. Season with salt and pepper. Place in another strainer and press lightly to remove any excess liquid. Pat dry with paper towels and let cool.
In a food processor, pulse the spinach and ricotta until smooth. Transfer the mixture to a bowl.
With a spatula, stir in the Parmesan, bread crumbs, flour, egg, salt and nutmeg. Season generously with pepper. If the dough is too sticky, add flour and bread crumbs. Shape into a disc and refrigerate for 15 minutes.
Divide the dough into 6 pieces. On a lightly floured surface, roll each piece into a long ½-inch (1 cm) thick rope. With a knife, cut each rope into ½-inch (1 cm) gnocchi. Lightly dust with flour. Set aside on a lightly floured baking sheet. The gnocchi may be frozen at this stage.
Into a large pot of salted simmering water, gently drop one-third of the gnocchi at a time. Once they float to the surface, let simmer for 2 minutes or until cooked through. With a slotted spoon, drain the gnocchi and add to warm Rosemary Rosée Sauce. Adjust the seasoning.