In a large skillet, melt the butter with the oil. Add the onion and ham. Cook about 3-4 minutes, or until onions are translucent. Add in the flour and whisk until golden brown.
Pour in the milk. Season with salt and pepper. Whisk until thickened, about 10 minutes.
Pour into a baking sheet and cool for 3 hours in the refrigerator.
Whisk eggs together in a dish. Place panko breadcrumbs on another dish. Season with salt, pepper, and nutmeg.
Shape the ham mixture into balls, about 2 TBSP each. Roll into the egg, then the panko.
Fry in 350 degree oil until golden brown, about 3-5 minutes.
