Combine the ingredients: Return the cooked beef to the skillet, along with the fresh spinach. Stir well and cook until the spinach is wilted (about 2 minutes).
Add the Parmesan: Sprinkle the grated Parmesan cheese over the mixture and stir to combine. If using, add red pepper flakes for extra heat.
Adjust seasoning and serve: Taste and adjust seasoning with more salt and black pepper if needed. Serve warm and enjoy!
Prep Time: 10 minutes | Cooking Time: 15 minutes | Total Time: 25 minutes
Kcal: ~450 per serving | Servings: 4