Cook grits according to package instructions. Turn off heat and add cheddar cheese, Parmesan cheese, butter, salt and peppers and tabasco sauce. Stir until mixed. Set aside, but keep warm.
Saute bacon in skillet, drain on paper towel, crumble and set aside.
Put olive oil in clean skillet. Pat shrimp dry. When oil is quite hot, place shrimp in an even layer in skillet, turning as they color. Add mushrooms and saute for about 4 minutes. Add scallions and garlic and saute for 1 minute more. Season with lemon juice and a dash more of tabasco sauce. Add parsley and salt and pepper to taste.
Divide grits over four plates. Spoon shrimp on top, sprinkle with bacon and serve immediately.