Place the chicken breast in the Instant Pot and set it for 12 minutes. (Alternative methods: bake or cook on the stovetop. The Instant Pot is preferred for tender chicken.)
Boil 1 lb of pasta until tender, following package instructions for al dente pasta. Drain and set aside.
In a medium saucepan, combine 1 cup of butter and 1 and 1/4 cup heavy cream over medium-low heat.
Use a whisk to blend the cream smoothly with the butter.
Gradually add 1 and 1/4 cup grated Parmesan cheese, whisking continuously until the cheese is fully melted and the sauce thickens.
Season with salt and pepper to your liking.
Return the cooked pasta to the pot or a deep pan.
Pour the Alfredo sauce over the pasta, stirring well to ensure each strand is generously coated with the creamy sauce.
Slice the cooked chicken breast into thin strips.
Arrange the sliced chicken on top of the pasta, evenly distributing it across the dish.
Optionally, garnish with fresh parsley, more grated Parmesan, or a sprinkle of black pepper.
Serve hot, directly from the stove to the table for the best flavor and consistency.