Microwave the French green beans in a bowl with water for 8–10 minutes until bright green and nearly tender. Drain and set aside.

In a large skillet over medium-high heat, combine olive oil and butter, letting it melt and heat for about 2 minutes.

Add the thinly sliced chicken thighs seasoned with salt and lemon pepper to the skillet. Cook for approximately 4 minutes on each side until browned and cooked through. Remove from pan and set aside.

Lower the heat to medium, add minced garlic and onion powder, stirring for 1 minute. Add precooked green beans and sliced mushrooms, cooking for an additional 4–5 minutes.

Pour in chicken broth and heavy cream, stirring to combine. Bring to a simmer over medium heat, letting it bubble for about 3–4 minutes until thickened.

Stir in grated Parmesan cheese, mixing until it melts into the sauce. Adjust seasoning as needed.

Return chicken to the skillet, allow it to warm in the sauce for 1–2 minutes. Serve hot, garnished with parsley if desired.