Cut tops off of tomatoes, hollow out insides, place upside down on bakers (over baking sheet) and bake 400° for 10 min. Set aside till ready to use.
Dice bacon,onion and mushroom. Cook bacon till almost done, add onions and mushrooms, cook till tender. Set aside.
Cook pasta per package directions.
Meanwhile heat butter in med. saucepan. Add flour and stir in, cook on low heat for a few minutes to remove the floury flavor. Add milk and stir constantly till all lumps are removed. Cook on low till sauce thickens. Add cheese to melt. Taste to add salt and pepper.
When pasta is done, drain and place back into pan. Pour cheese sauce over and mix well, add bacon mixture and mix in. Place pasta into tomatoes and garnish with a little extra cheese and pop in micro to melt.