Preheat oven to 375 degrees.
De-stem and clean mushrooms.
On a greased cookie sheet, place mushrooms and bake for 10 minutes.
Remove from the oven and drain liquid from mushrooms.

Combine mayonnaise, Asiago cheese, basil and pepper in a food processor and blend.
Place a teaspoon of the mixture in each mushroom.
Place a tomato half on top of each mushroom.
Place in oven and bake for 8-10 minutes or until cheese mixture is golden brown.