In a saucepan, sauté onions and squash in olive oil over medium heat until soft, about 5 minutes. Add mushrooms and sauté about 5 minutes or until mushrooms are lightly browned.
Stir in flour and cook for 2 minutes, stirring constantly to avoid scorching. Remove from heat for 2 minutes and slowly add ˝ cup vegetable broth.
Return to heat and gradually add the remaining broth. Cook for about 5 minutes. Stir in sour cream (it okay to add more than ˝ cup if you like it creamier).
Serve over cooked noodles or brown rice.
Serving Size: 1/4 of sauce with 1 cup cooked noodles.
