Preheat oven at 375*.
Melt 2 Tablespoons butter in a hot cast iron skillet.
Toss in cut asparagus and chopped onions. Constantly stirring, sauté until tender, about 5-8 minutes.
Whisk eggs, milk, flour, baking soda, and spices until well-blended (no lumps).
Generously grease all sides and bottom of a 9 inch glass pie plate with 2 tablespoons butter. Sprinkle grated Parmesan cheese on the bottom of the pie pan.
Combine sautéed asparagus, onions, and cheddar cheese with egg mixture.
Carefully pour egg mixture into pie plate.
Bake for 20-25 minutes, or until eggs are cooked completely.
