Stuffed Mushrooms (1)

1 package of large stuffing mushrooms or two large portabella mushroom caps (remove stems)
1 package frozen, chopped spinach thawed and drained (squeeze out all the water)
1/3 cup shredded cheese (Swiss, cheddar, or Monterey Jack)
1/4 cup bread crumbs (or cold cooked rice)
1 teaspoon lemon juice or vinegar
Salt and pepper

Place mushrooms, cap side down in a greased dish or cookie sheet and bake in oven at 350 degrees for 10 minutes. Remove from oven and let cool for a few minutes. Mix together filling ingredients and spoon into mushroom caps, packing the stuffing in and filling down. Return to oven and bake for another 10 minutes.