Start by bringing a large pot of salted water to a boil. Once boiling, add spaghetti and cook until al dente (8-10 minutes). Drain and set aside.

In a large skillet, heat olive oil over medium heat. Season chicken with salt and pepper, cook for 5-7 minutes per side until golden brown and internal temperature reaches 165°F (74°C). Slice chicken into strips.

In the same skillet, add olive oil if needed, and sauté diced onion and minced garlic for 2-3 minutes until onion is translucent.

Pour in chicken broth and bring to a simmer. Then whisk in heavy cream and shredded Monterey Jack cheese until melted and creamy.

Add halved cherry tomatoes and fresh spinach, cook for 3-4 minutes until spinach is wilted.

Combine sliced chicken and drained spaghetti with the sauce, toss gently to coat.

Taste and adjust seasoning with salt and pepper. Serve hot, garnished with Parmesan cheese and fresh parsley or cilantro.