Combine breadcrumbs and 1/2 cup of Parmesan cheese and spread out on a plate. Heat oil in a heavy skillet over medium heat. Cut chicken breasts in half and pound to 1/2 inch. Dip chicken pieces in egg and coat both sides with the bread crumb mixture. Cook chicken pieces (about 3 minutes each side) and place on paper towels to drain.
Saute onion and garlic in 1 tbs butter until onion is clear and add nutmeg and spinach. Cook until combined and heated through. Spread spinach mixture on the bottom of a oiled baking pan large enough to accommodate the chicken pieces.
For the cream sauce, make a roux from the 2 tbs butter and 2 tbs flour cook for about one minute then increase heat and add the wine and whip with a wisk until smooth then dry. Slowly begin adding the milk until it is all incorporated, whisking constantly. Add the cheese and nutmeg and cook until thick and creamy.
Assembly: Pour half of the sauce over the spinach and place chicken on top then top with the remaining sauce. Place dish in the oven and cook until bubbling, about 30 minutes. Serve with pasta or rice.