Chicken breast in spinach sauce

Chicken breast (the recipe asks for 10 steaks of chicken breast, but it's just 2 of us, so I just made 4)
1/2 lime or lemon
salt/pepper
butter

Spinach sauce

1/2 a pack of spinach (supermarket packs) or 1 bunch of spinach, cooked and drained
1 tbspoon of finnely chopped onion
1 clove of garlic, finnely chopped
2 tbspoons of butter
1 tbspoon of flour
700ml of milk (I used less, since I made half the recipe for just 2 people...so I used around 300ml)
salt and pepper
parmesan to sprinkle on top of it all
double cream (about 2 tbspoons) - optional...I made mine yesterday without and it was really good (I didn't have any at home and my spinach wasn't going to last another day)

Blend the spinach and the milk. In a pan, fry the garlic and onion in the butter. Add the spinach and milk mix. In a small glass, mix the flour in a bit of milk. Add to the pan stirring well. Let it thicken and check the salt and pepper. If you are adding the double cream, turn off the hob and add it.

Season the chicken breast with the lime/lemon, salt and pepper. Fry them in butter. Serve the chicken and put the sauce on top. Sprinkle it with (a lot of) parmesan.