Cook the spaghetti according to package instructions. Drain and set aside.

Heat olive oil in a large skillet over medium heat. Season the chicken breasts with salt, pepper, and smoked paprika. Cook the chicken in the skillet for 6-7 minutes on each side until fully cooked. Remove from the skillet, slice into strips, and set aside.

In the same skillet, melt butter and sauté the diced onions and minced garlic for 2-3 minutes until softened.

Add the chicken broth and bring to a simmer. Stir in the heavy cream and cook for another 2 minutes, allowing it to thicken slightly.

Reduce the heat to low, then stir in the shredded Monterey Jack cheese and Parmesan cheese until melted and smooth.

Add the cooked spaghetti to the skillet and toss to coat in the creamy sauce.

Top with sliced chicken, sprinkle with parsley, and add crushed red pepper flakes if desired.

Serve hot and enjoy!