Heat a sauté pan over medium heat. Add butter and olive oil and when butter is melted and oil is warm, add onion. Sauté onion until softened and translucent, about 5 minutes. Add ¼ cup flour and whisk until browned and nutty, one to two minutes.

Very slowly whisk in milk, a little at a time to avoid a lumpy sauce. Season with a little salt, pepper and a pinch of nutmeg (remember that the ham is salty, so go easy on the salt at first). Continue to whisk constantly until sauce has thickened, 10-15 minutes. When sauce has thickened, stir in ham. Taste and add more seasoning if needed.

Pour sauce into a baking sheet and allow to cool, then refrigerate for at least 3 hours (can also be done the day before cooking).

When ready to cook, preheat oven to 200°F and prepare a baking sheet fitted with a cooling rack. This is for keeping the croquettas warm after frying until you are ready to serve.

Prepare a breading station by whisking eggs in one dish and placing breadcrumbs into a shallow dish, and ½ cup flour in another dish. Shape the dough into 1-2 tablespoon sized, football shaped balls. Roll in the flour, then in the egg, then in the breadcrumbs.

In a heavy pot or deep fryer, bring oil to 350°F degrees.

Add up to six, one at a time, into the oil and fry until golden brown, 2-3 minutes. When removing from oil, place onto prepared rack and leave in the warm oven until ready to serve.

These are best served fresh!