Preheat your oven to 375°F (190°C).

In a mixing bowl, combine the chopped spinach, softened cream cheese, mozzarella cheese, garlic powder, and a pinch of salt and pepper. Mix until everything is well combined and creamy.

Using a sharp knife, carefully slice a pocket into each chicken breast. Fill each pocket with the creamy spinach mixture, being careful not to overstuff. Secure with toothpicks if necessary.

In a large oven-safe skillet, heat a tablespoon of olive oil over medium-high heat. Add the stuffed chicken breasts and sear for about 4-5 minutes on each side until golden brown.

Transfer the skillet to the preheated oven and bake the chicken for around 20-25 minutes, or until the internal temperature reaches 165°F (75°C).

While the chicken is baking, cook the rigatoni according to package instructions until al dente. Drain and set aside.

In a medium saucepan, heat a tablespoon of olive oil and sauté the minced garlic for 1 minute. Add the chopped spinach and cook until wilted. Pour in the heavy cream, stirring constantly, and bring to a gentle simmer. Stir in the Parmesan cheese, salt, and pepper to taste.

Add the cooked rigatoni to the creamy spinach sauce, tossing to coat. Once the chicken is cooked, slice it and serve atop a generous portion of creamy rigatoni.