To your pan add the diced onion and garlic. Cook until the onion is soft.
1/4 cup onion, 2 cloves garlic
Add the butter, cream, last of the cajun seasoning, and cheese. Whisk to combine.
2 tablespoons butter, 1 cup heavy cream, 3 oz parmesan cheese, 1/2 teaspoon Cajun seasoning, 2 oz mozzarella cheese
After the cheese has melted add the chicken. Cook on one side for 2.5 minutes. Add the spinach and flip the chicken and cook to desired doneness (approximately another 2.5 minutes).