In large pot or saucepan, melt butter, add shallots and leeks and sauté until wilted, about 2-3 minutes.
Whisk in broth, milk, wine and lemon juice. Bring to boil, continue whisking, 2-3 minutes.
Add cream cheese, sage, thyme, nutmeg, pepper, salt, brandy and pumpkin puree. Bring to boil, whisk to smooth sauce. Whisk in parmesan cheese, and keep warm while cooking pasta.
Add cooked pasta to bowl, add as much sauce as you like and toss gently to mix. Season with additional salt and pepper, if needed. Sprinkle additional Parmesan cheese on top, if desired.