Preheat oven to 180 degrees C
Slice chicken to make 8 pieces
Dust chicken with flour, salt and pepper
Heat butter in a frying pan. Add garlic and chicken, cooking gently until golden
Add wine and bring to the boil. Reduce to a gentle simmer and cook, covered for 10 minutes
Move chicken to ovenproof dish, leaving liquid in the pan. Put slice of proscuitto then a slice of cheese on each piece of chicken. Cook in the oven for around 10 minutes, until cheese is melted
Bring liquid in the pan to a low simmer. Add cream, mustard and green onions. Stir until combined and season with salt and pepper
Pour sauce over chicken to serve.