Step 1: Cook the Pasta - Bring a large pot of salted water to a boil. Add the fusili or rotini pasta and cook according to package instructions until al dente. Drain and set aside, reserving a cup of pasta water.
Step 2: Sauté the Chicken - In a large skillet, heat olive oil over medium heat. Add diced chicken, season with salt, pepper, and thyme. Cook for 5-7 minutes until golden brown. Remove and set aside.
Step 3: Make the Cheese Sauce - In the same skillet, melt butter, add minced garlic, and sauté for 30 seconds. Sprinkle in flour, whisk for a minute. Gradually whisk in milk until thickened. Stir in cheeses and herbs until melted.
Step 4: Combine Everything - Return chicken and pasta to the skillet with cheese sauce. Toss gently until coated. Adjust seasoning with salt and pepper.
Step 5: Serve and Enjoy! - Spoon portions into bowls, garnish with thyme or Parmesan, and serve warm.