Bacon Cheddar Mushrooms

3 slices bacon
8 large mushrooms
1 T. butter
1 T. chopped onions
3/4 C. shredded Cheddar cheese, divided

Preheat grill to 400°. In a large skillet over medium high heat, cook bacon slices until evenly browned. Remove bacon from skillet and let drain on paper towels. Finely dice the drained bacon. Remove stems from mushrooms and chop stems into pieces. Set mushroom caps aside. In a large saucepan over medium heat, place butter. Heat butter until melted and add chopped mushrooms stems and chopped onions. Sauté mushrooms and onions until softened. Remove from heat and place sauté mixture in a medium bowl. Add diced bacon and 1/2 cup shredded Cheddar cheese. Mix well and scoop mixture into mushroom caps. Place filled mushroom caps on an ungreased baking sheet. Bake in covered grill for 15 minutes, until cheese has melted. Remove mushrooms from grill and sprinkle with remaining 1/4 cup shredded Cheddar cheese.