Bring a large pot of salted water to a boil.
Heat the cream in a medium saucepan and add the cooked cauliflower. Simmer the cream for a minute or two until the cauliflower is heated.
Add cream and cauliflower to a blender and puree until smooth. Add the ricotta and blend again.
Return the puree to the pan. Whisk in the salt, pepper, and nutmeg. Keep sauce hot while you cook the pasta.
Boil the capellini for 3 minutes or according to package directions. Set aside ¼ cup of the hot pasta water.
Drain pasta, then toss with the creamy cauliflower sauce and the hot pasta water. Serve immediately.
