Spinach-Filled Mushrooms - cooking recipe

Ingredients

16 to 20 mushrooms (1 1/2 to 2 inches)
1 c. finely chopped onion
3 Tbsp. butter or margarine
1 (10 oz.) pkg. chopped frozen spinach, cooked according to pkg. directions and drained
1/2 c. grated Swiss cheese
grated Parmesan cheese

Preparation

Remove stems from mushrooms.
Chop stems finely and saute with onion in butter until tender, but not brown.
Add spinach.
Stir to mix thoroughly.
Add Swiss cheese, stirring lightly.
Remove from heat.