Prepare the Chicken
Cut the boneless, skinless chicken breasts or thighs into thick strips.
Season the chicken with salt, pepper, Italian seasoning, and minced garlic, making sure the pieces are evenly coated.
Allowing the chicken to sit with the seasonings for a few minutes gives the garlic and herbs time to flavor the surface.
Cook the Spaghetti
Bring a large pot of salted water to a boil.
Add the spaghetti and cook until tender but still slightly firm.
Drain the pasta once cooked and set it aside.
Avoid overcooking the spaghetti because it will continue to absorb some of the creamy cheese sauce later.
Cook the Garlic Herb Chicken
Heat a large skillet over medium-high heat and cook the seasoned chicken strips until golden on the outside and fully cooked through.
Turn the pieces as they cook so they develop color on multiple sides.
Once cooked, remove the chicken from the skillet and set it aside.
Keeping the chicken separate while preparing the sauce helps prevent it from becoming overcooked.
Start the Cream Sauce
Reduce the heat to medium-low.
Add the heavy cream to the skillet and stir, incorporating the flavorful browned bits left behind by the chicken.
Add the remaining garlic and Italian seasoning if needed, then season lightly with salt and pepper.
Allow the cream to warm gently.
Add the Cheddar and Parmesan
Gradually add the shredded sharp cheddar, stirring continuously as it melts.
Once the cheddar has melted into the cream, add the grated Parmesan.
Continue stirring gently until the sauce becomes smooth, creamy, and rich.
Avoid boiling the sauce once the cheese has been added. Gentle heat helps maintain a smoother texture.
Add the Spaghetti
Add the cooked spaghetti to the creamy cheddar sauce.
Toss thoroughly until every strand is generously coated.
If the sauce is particularly thick, a small splash of reserved pasta water can be used to loosen it and help the sauce cling beautifully to the spaghetti.
Add the Chicken
Return the cooked garlic herb chicken strips to the skillet.
Gently toss or arrange the chicken over the creamy spaghetti so that the chicken remains visible while the pasta absorbs the rich cheese sauce.
Finish with Fresh Herbs
Transfer the pasta and chicken to serving plates.
Scatter fresh basil and parsley over the top.
For an extra cheesy presentation, finish with a light dusting of Parmesan just before serving.
Serve immediately while the sauce is warm, creamy, and wonderfully cheesy.