In a large mixing bowl, combine the flour and salt. Make a well in the center and crack the eggs into the well. Use a fork to beat the eggs gently, then gradually incorporate the flour until a dough forms.
Knead the dough on a floured surface for about 5-10 minutes until smooth. Wrap in plastic wrap and let it rest for 30 minutes.
In a skillet, sauté the chopped spinach over medium heat until wilted, about 2-3 minutes. Allow it to cool slightly.
Mix the sautéed spinach with ricotta, Parmesan cheese, salt, pepper, and nutmeg in a bowl until well combined.
Use a rolling pin or a pasta machine to roll out the dough into thin sheets (about 1/16 inch thick). Cut the sheets into large squares or circles.
Place a small spoonful of filling (about 1 tablespoon) in the center of each pasta square. Moisten the edges with a little water, fold the pasta over to form a pocket, and press firmly to seal.
Bring a large pot of salted water to a boil. Carefully add the ravioli in batches and cook for 3-4 minutes until they float to the surface and are tender.
Use a slotted spoon to remove the ravioli and transfer them to a baking sheet.
Toss the cooked ravioli with your choice of pasta sauce and top with grated Parmesan cheese. Serve hot.