8 oz. medium egg noodles
4 T. butter, divided
1 c. chopped onion
2-1/2 to 3 c. diced corned beef (about 12 oz.)
16 oz. chopped frozen spinach, thawed, excess water squeezed out
3 T. all-purpose flour
1 c. chicken broth
1 c. milk
1/8 tsp. black pepper
1/4 tsp. dried leaf thyme
2 c. shredded sharp cheddar cheese
1/2 tsp. salt
1/2 to 1 c. French-fried onion rings or buttered bread crumbs (optional)
Using a large saucepan or stockpot, cook noodles following package directions; drain well. Put noodles back in pot and set aside.
In a medium saucepan, melt 2 Tablespoons of butter over medium-low heat; cook onion for two minutes. Add corned beef and cook until lightly browned. With a slotted spoon, transfer beef mixture to the pot with noodles. Add the squeezed spinach to the pot and set aside.
In the same medium saucepan, melt remaining two tablespoons butter over medium-low heat; stir in flour until well blended and bubbly. Stir in chicken broth and milk. Cook, stirring constantly, until thickened and bubbly. Add pepper and thyme. Stir in the cheese, cooking until melted. Add salt to taste. Pour sauce over the noodle and corned beef mixture; stir until well blended. Spoon the noodle mixture into prepared baking pan. If desired, top with crumbled French-fried onion rings or buttered breadcrumbs.
Bake for 30 minutes, or until hot and lightly browned.