Combine chicken breast, dijon mustard, salt, black pepper, onion powder, and garlic powder in a bowl. Mix well.
Heat olive oil and butter in a large skillet or pot over medium-high heat.
Add chicken and cook until browned on both sides.
Remove chicken from the pot and set aside.
Add chopped yellow onion to the pot and cook until softened, about 3-4 minutes.
Add minced garlic and cook for another minute until fragrant.
Stir in long grain rice and Italian seasoning, toasting for about 1 minute.
Pour in chicken broth and bring to a simmer.
Return the chicken to the pot.
Cover and reduce heat to low. Cook for 15-20 minutes, or until rice is cooked and liquid is absorbed.
Stir in heavy cream, grated parmesan, and lemon juice.
Add spinach and cook until wilted.
Garnish with fresh parsley before serving.
