In a skillet, heat oil at medium-high heat. Add onions, garlic, mushroom, salt, italian herbs and pepper. Cook, stirring, for about 6 minutes or until mushrooms are golden.
Put slices of baguette on a baking sheet and sprinkle them with half the cheese. Spread on the slices of bread 1/2 cup of basil leaves, the mixture of mushrooms and tomatoes. Sprinkle with remaining cheese.
Cook in a preheated oven of 400 F for 10 minutes or until cheese has melted. Cut remaining basil leaves in fine strips and sprinkle on hot pizzas.