Cook a 16 oz box of penne rigate in a large pot according to package directions.
While the pasta is cooking, cook the chicken. Heat the olive oil in a large frying pan and cook the bite sized pieces of chicken breasts until they are cooked through.
Preheat the oven to 400 degrees.
Drain the pasta when done cooking and return to the pot. Add in the cooked chicken, pesto sauce, salt, pepper and garlic powder. Stir to combine.
Pour the contents into a 9x13 greased casserole dish.
Top with the shredded mozzarella cheese.
Bake in a 400 degree oven for 10-15 minutes to melt the cheese.