World's Easiest Souffle

This is a favorite recipe from the American Egg Board.

Butter
Grated Parmesan cheese
4 eggs
4 ounces sharp Cheddar cheese, cubed
3 ounces cream cheese, cubed
1/3 cup milk, light cream or half-and-half
1/4 cup grated Parmesan cheese
1/2 teaspoon onion salt
1/2 teaspoon dry mustard

Butter bottom and sides of 1-quart soufflé dish or casserole. Dust with Parmesan cheese. Set aside.

Combine remaining ingredients in blender container. Cover and blend at medium speed until smooth, about 30 seconds. Blend at high speed another 10 to 15 seconds. Carefully pour into prepared dish. Bake in preheated 350 degrees F oven 25 to 30 minutes or until puffy and delicately browned.

Serve immediately.