Mix together the almond flour, 1 cup of Parmesan cheese, onion powder, and Italian herbs in a bowl to combine. Set aside.
Lay a piece of plastic wrap onto a chopping board and place a chicken breast on top. Then layer another piece of plastic wrap over that to cover it. Pound the chicken with a rolling pin or meat mallet to flatten it to approx 1/4-inch thickness. Repeat this step with each chicken breast.
Remove the top layer of plastic wrap, then place two pieces of Swiss cheese on the flattened chicken, then place two pieces of ham on top.
Roll the chicken, cheese, and ham up into a sausage shape, with the plastic wrap still around it (this will help maintain the shape). Repeat with the remaining chicken breasts.
Unwrap each chicken breast and roll it first in the beaten egg, and then in the almond flour/Parmesan mixture.
Preheat the oven to 350 F.
Heat the vegetable oil in a large frying pan on a medium setting. Fry the chicken for a few minutes on each side, until browned all over.
Place the chicken on a baking sheet and bake for 20 minutes or until cooked through (ensure the chicken is piping hot and no longer pink in the middle when you slice into it).
Whilst the chicken is baking, make the sauce. Melt the butter in a saucepan over a medium heat. Then, add the garlic and cook for 1 minute, stirring constantly.
Add the cream, mustard, remaining 1/2 cup of Parmesan cheese, and any salt and pepper to taste. Stir well and let it simmer for 5 minutes until slightly thickened. The sauce will thicken up more as it cools.
Spoon the sauce over the chicken. You can serve each piece whole or slice into rounds.