1. Bring large pot of salted water to the boil.
2. Heat butter and olive oil in a pan over medium heat. Add diced onion and saute for 2-3 minutes. Add garlic, red pepper flakes, nutmeg, salt, pepper, lemon zest and lemon juice. Then add the white wine slowly. Let simmer for 1-2 minutes before adding the asparagus and cooking for a further for 5-6 minutes.
3. Meanwhile add the pasta to boiling water, cooking according to package directions. Drain, but retain the pasta water for later
4. Add frozen peas to saute pan with your asparagus.
5. In a medium sized bowl, whisk together ricotta and 1/3 cup reserved pasta water.
6. Drain pasta, add ricotta mixture, and vegetable mixture then stir. Serve with parmesan to top.