Preheat an oven to 300 degrees F (150 degrees C). Stir the ricotta cheese, mozzarella cheese, garlic, salt, and pepper in a bowl; set aside on counter to allow to come to room temperature. Bring a pot of water to a boil; cook the penne in the boiling water until cooked through yet firm to the bite, about 11 minutes. Drain and transfer to a large mixing bowl. While the pasta cooks, place a skillet over medium heat. Crumble the turkey into the skillet; cook and stir until the turkey is completely browned.
Drain and add to the pasta. Spread 2 tablespoons of the spaghetti sauce into the bottom of a 13x9-inch baking dish; stir the rest of the spaghetti sauce into the pasta and turkey mixture.Spoon about half of the pasta mixture into the baking dish; top with the cheese mixture and spread into an even layer. Spread the remaining pasta mixture over the cheese layer. Cover with aluminum foil if desired. Bake in the preheated oven until slightly brown on top, about 30 minutes.