Preheat your oven to 350°F (175°C).
Prepare the pasta according to package instructions until al dente.
In a large saucepan, melt the butter over medium heat.
Stir in the flour and cook for about 1-2 minutes, until lightly golden.
Gradually whisk in the chicken broth, stirring continuously until smooth.
Add the heavy cream and bring the mixture to a simmer.
Stir in the Parmesan cheese, garlic powder, salt, and pepper.
Combine the cooked chicken, peas, and pasta in a large mixing bowl.
Pour the cream sauce over the pasta mixture and stir until everything is well coated.
Transfer the mixture to a greased baking dish.
Bake in the preheated oven for 25-30 minutes, until golden and bubbly.
Let it rest for a few minutes before serving.
