Serves 8 as a tapa
Makes about 16
2 tablespoons unsalted butter
2 tablespoons olive oil
1/4 cup finely chopped onion
Coarse salt and freshly ground pepper
7 tablespoons all-purpose flour, plus more for shaping
1 3/4 cup whole milk
6 tablespoons finely chopped serrano ham
1/3 cup grated plus 1/4 cup Manchego cheese, (about 1 3/4 ounces)
3 large eggs
1 1/2 cups fresh breadcrumbs
Vegetable oil, for frying
Fresh flat-leaf parsley sprigs, for garnish
In a food processor process first the cheese into fine crumbs. Clean the bowl then process the ham until finely minced. Set both aside until needed.
Heat butter and oil in a medium saucepan over medium heat until butter has melted. Add onion; season with salt and pepper. Cook, stirring occasionally, until onion is translucent, about 3 minutes. Add flour; cook, stirring, 1 minute. Whisk in milk, and cook, whisking, 3 minutes. Whisk in ham and 1/3 cup cheese. Season with salt and pepper as desired. Spread mixture onto a baking sheet, and let cool completely. Mixture can be refrigerated in an airtight container up to 2 days. Croquettes must be very cold before you go to the next step. I usually make them one day and bread them the next.
Whisk together eggs in a shallow dish. Stir together breadcrumbs and remaining 1/4 cup cheese in another shallow dish. Scoop tablespoons of cooled mixture, and shape with floured hands into 2-inch ovals. Working with 1 oval at a time, coat in beaten egg, then in breadcrumb mixture. Transfer to a baking sheet lined with parchment paper.
Heat 2 1/2 inches oil in a large, heavy stockpot until it registers 375 degrees on a deep-fry thermometer. Working in batches to avoid crowding, fry croquettes, flipping once, until dark golden brown, 1 to 2 minutes total. Using a slotted spoon, transfer to paper towels to drain. (Adjust heat between batches as needed to keep oil at a steady temperature.) Serve warm, garnished with parsley sprigs. Accompany with fig marmelade.