A hundred years ago celery was often served as a cooked vegetable, so I decided to make a recipe for Celery au Gratin that I found in a 1922 cookbook.
The Celery au Gratin was tasty with pieces of celery embedded in a delightful cheese sauce.
Here is the original recipe:

I used butter instead of shortening when making the sauce for this recipe.
Here’s the recipe updated for modern cooks:
Celery as Gratin
2 cups celery, cut into 1-inch pieces
2 cups water
1/2 teaspoon salt
1/2 cup milk
2 tablespoons butter + 1 tablespoon butter
2 tablespoons flour
dash salt and pepper
3/4 cup grated cheese (I used cheddar.)
1/2 cup fine soft bread crumbs
Preheat oven to 375° F. Put celery pieces, water and 1/2 teaspoon salt in a saucepan. Bring to a boil using high heat, then reduce heat and simmer until the celery is tender (about 10 minutes). Then remove from heat, and drain, reserving 1/2 cup of the liquid to use in the sauce. Set aside.
Melt 2 tablespoons butter in another saucepan, then stir in flour and dashes of salt and pepper. Gradually, add the milk and reserved celery liquid while stirring constantly; Continue heating and stirring using medium heat until the sauce thickens.
Put half the cooked celery in a 3-cup casserole dish; add 1/2 of the sauce, then top with 1/2 of the grated cheese. Repeat in same order. Set aside.
Melt 1 tablespoons butter in a small saucepan. Add the breadcrumbs and stir. Continue stirring until the breadcrumbs are crispy and light brown.
Sprinkle the buttered breadcrumbs on top of the layered celery. Put in oven and bake for approximately 20 minutes or until hot and bubbly.