Preheat your grill to the highest setting. Season the chicken all over with salt and pepper, then sprinkle it with the garlic powder.
Grill the chicken for 5 to 6 minutes per side, or until the internal temperature registers 165 degrees F. Let rest for 20 minutes before chopping. Alternatively, you can use rotisserie chicken or pre-cooked chicken for this recipe.
Preheat the oven to 400 degrees F. Spray a 9x13 inch baking dish with nonstick spray.
Bring a pot of salted water to a boil and cook the pasta according to the package directions. Cook it until al dente, then drain.
While the pasta is boiling, add the pesto to the baking dish. Pour in the cream and whisk until fully combined.
Add the cooked pasta to the dish and toss well, until every piece is coated in the sauce.
Add the tomatoes and grilled chicken on top. Toss well. Add in 1 ½ cups of the mozzarella cheese and the parmesan cheese. Stir and mix well until the cheese is dispersed throughout the pasta.
Top the pasta with the remaining mozzarella. Bake for 20 to 25 minutes, or until golden and bubbly. Let cool slightly before serving. Top with extra parmesan if desired.