Cut chicken into bite size pieces and cook in a little olive oil, salt and pepper until opaque.

Mix in rest of ingredients except for portobellos and mozzarella cheese and simmer for 30 minutes.

Remove stems and clean out gills with a spoon. Baste with olive oil and put in oven at 350°F for 10 minutes.

Remove portobellos from oven and fill with mixture and top with cheese. Put back in oven for 15 minutes or until cheese is melted and slightly browned.