Step 1

Grease a casserole dish and preheat oven to 350 degrees.

Step 2

Melt butter in a large pan over medium heat. Add asparagus, mushrooms, and onions and cook, stirring occasionally, for about 6 minutes.

Step 3

Sprinkle flour over vegetables and cook, stirring continuously, for 1 to 2 minutes.

Step 4

Gradually stir in milk. Cook until thickened.

Step 5

Reduce heat to low and mix in mayonnaise, sour cream, both cheeses, salt, lemon pepper, and paprika. Remove from heat.

Step 6

Crush about 1/3 of the can of french-fried onions and mix them into the asparagus mixture.

Step 7

Transfer mixture to prepared casserole dish.

Step 8

Sprinkle remaining french-fried onions on top.

Step 9

Place in oven and bake for 30 minutes.