Brussels Sprout-Squash Casserole

1 lb sprouts
1 1/2 cups winter squash
1 onion minced
1 cup celery
1 tsp butter
2 tsp oil
1/4 cup whole wheat flour
2 cups milk
1/2 tsp marjoram
pepper and nutmeg

Steam sprouts and squash separately. Preheat oven to 350F. Sauté onion in butter and oil, add flour and cook slowly for 3 minutes. Add milk and spices, bring mixture to a boil and remove from heat. Arrange squash then sprouts in a baking dish, sprinkle chopped celery on top, pour sauce over veggies and top with a sprinkle of nutmeg.