Chicken Florentine Mac and Cheese

Name: Chicken Florentine Mac and Cheese
Ingredients: 1 pound elbow macaroni; 6 tablespoons salted butter; 1 pound boneless, skinless chicken breast, cut into small cubes; Kosher salt and freshly ground black pepper; 2 cloves garlic, minced; 1/2 cup chicken stock; 2 cups whole milk; 1/2 cup heavy cream; 1 cup shredded white Cheddar; 1 cup shredded fontina cheese; 2 teaspoons cornstarch; 8 ounces white processed cheese, such as Velveeta or queso blanco, cubed; 3 cups baby spinach; 1 1/2 cups halved cherry tomatoes; 1/4 cup chopped fresh parsley