Finely chop the garlic and onion and fry in 1 teaspoon olive oil. Add spinach and season well with salt, pepper and nutmeg.
Cut open the chicken breast fillet, pound until flat, season with salt, pepper and brush with 1 teaspoon of mustard. Dice the mozzarella and spread over the meat with the spinach. Roll up and secure with wooden sticks.
Fry the filled chicken breast in 1 teaspoon olive oil and cook in a preheated oven at 180 degrees for about 10 minutes.
For the sauce, finely chop the red onion and fry half in 1 teaspoon olive oil. Pour in the stock, bring to the boil, stir in the cheese and parsley and season with salt, pepper, sugar and nutmeg.
A fresh tomato salad and ciabatta bread goes well with it.