In a medium saucepan, heat the butter and olive oil over medium heat until the butter melts.

Add the flour and cook, stirring constantly, for about 3 minutes.

Gradually add the milk and chicken broth (or vegetable broth) to the saucepan.

Season with salt, black pepper, nutmeg, and cinnamon.

Continue stirring constantly until the sauce is thickened and smooth.

Reduce the heat to low, then add the chopped Serrano ham, chicken, and pork.

Cook, stirring occasionally, for about 10 minutes.

Spread the mixture out on a dinner plate and let it cool.

Refrigerate until firm enough to handle.

With floured hands, shape the pork mixture into 1-inch balls.

Place the eggs and bread crumbs in separate shallow bowls.

Heat at least 1 inch of oil in a large skillet over medium-high heat (or use a deep fryer set at 365°F) until it turns a cube of bread light brown in 60 seconds.

Dip each croquette into the beaten eggs, dredge in the bread crumbs, and place in the hot oil.

Cook the croquettes, turning several times, until they become golden.

Transfer the fried croquettes with a slotted spoon to paper towels to drain.

Serve hot.