Winter Squash Mac and Cheese

8-12 oz macaroni, cooked until al dente, drained
2-3 Delicata squash, halved, seeded, roasted, & mashed
2 onions, thinly sliced
6 TBLS butter
2 TBLS flour
2 cups milk
2 cups cheddar cheese, grated
breadcrumbs and additional cheese to top (optional)

In large skillet, sauté onions in 2 TBLS butter until golden brown, stirring to prevent sticking.  Remove.  Melt 4 TBLS butter, add flour, and stir into paste.  Add milk and whisk 2 min.  Add salt and pepper.  Add squash and cheese and mix until combined into a sauce.  Stir in macaroni.  Top with optional breadcrumbs/cheese.  Bake at 400 to warm through, 20 min.