Put the spinach and ricotta or curd cheese in a food processor with the nutmeg, salt and pepper to taste and process until smooth. Cover and refrigerate while you roll out the pasta dough.
Roll the pasta dough out into long sheets (see
Cook the pasta in a large saucepan of salted boiling water for 2–3 minutes until al dente. Drain thoroughly, return to the pan and toss with the melted butter. Divide between 4 warmed serving plates and serve immediately with a scattering of grated Parmesan.