Begin by boiling a large pot of salted water. Once boiling, add the dried penne and cook according to the package instructions until al dente. Drain and set aside.
In a large skillet, melt the butter over medium heat. Once melted, add the minced garlic and sauté for about 1 minute until fragrant.
Sprinkle the flour over the melted butter and garlic, whisking constantly for about 2-3 minutes to create a roux.
Gradually pour in the half & half while continuing to whisk. Bring the mixture to a simmer and let it thicken, about 5-7 minutes.
Stir in the Italian seasoning and chicken bouillon, mixing well to combine all flavors.
Remove the skillet from heat and fold in 2 cups of shredded mozzarella and the grated parmesan until melted and smooth. Then add the chopped chicken and cooked pasta, stirring until well coated.
Preheat your oven to 350°F (175°C). Transfer the pasta mixture into the prepared baking dish, spreading evenly. Sprinkle the remaining 1 cup of mozzarella cheese on top.
Bake in the oven for 25-30 minutes, or until the cheese is bubbly and golden.
Let the dish cool for a few minutes. Garnish with fresh parsley before serving.