2 teaspoons lemon juice 1/4 cup all-purpose flour 2 cups milk
1 cup shredded cheddar cheese 1/2 cup soft bread crumbs
Directions
In a small saucepan, combine the onions, water and salt. Cover and cook for 20 minutes or until crisp-tender; drain. Transfer to two greased 1-qt. baking pans; set aside. In a skillet, saute mushrooms in 4 tablespoons butter and lemon juice. In a small saucepan, melt 4 tablespoons butter; stir in flour until smooth. Gradually add milk. Bring to a boil; cook and stir for 2 minutes or until thickened. Stir into mushroom mixture. Pour over onions. Melt the remaining butter. Add cheese and bread crumbs; toss to coat. Sprinkle over each casserole. Cover and freeze one casserole for up to 3 months. Cover and bake the second casserole at 375 degrees F for 15 minutes. Uncover; bake 10 minutes longer or until golden brown.
To use frozen casserole: Thaw in the refrigerator for 8 hours. Bake as directed.