Preheat oven to 350 and lightly grease a 9x 13 baking dish (or two smaller baking dishes.)
Wash and slice the veggies. Cut mini breads along the center but not all the way through. (I also like to take out some of the soft bread center to make more room for the filling but that's optional.)
Preheat a large cooking pan oven medium heat and add vegetable oil.
Saute sliced onion and peppers until starts to soften and add sliced mushrooms. Add salt and pepper to taste and cook, stirring occasionally, until fully cooked. Take off heat.
Break up the garlic and herb cheese into the pan with veggies and stir until completely incorporated.
Divide cheesy veggie filling among the rolls.
Place mini sandwiches into the baking dish (dishes) and bake them for about 15 minutes.