Place the chicken in a skillet with a little oil and cook it. Then cut it into small cubes.

Sauté the onion, diced, over medium-low heat until golden. Add a teaspoon of sugar and let it caramelize, being careful not to burn it.

Once the filling is ready, make the béchamel by melting the butter with the oil over medium heat until fully melted.

Add the flour and stir until no dry flour remains.

Add 1 cup of the total milk, preheated to prevent lumps. Stir until smooth.

Pour in the rest of the milk and stir until the mixture thickens and you can see the bottom of the pan for a second or two when stirring.

Season with salt, pepper, and nutmeg to taste, then add the chicken and caramelized onion.

Transfer the mixture to a dish and cover directly with plastic wrap. Refrigerate for about 4 hours, though I like to leave it overnight.

Remove from the fridge and shape the mixture into croquettes. Coat each one first in breadcrumbs, then in beaten egg, and again in breadcrumbs.

Let them rest for 30 minutes, then fry in plenty of sunflower oil, making sure they are fully submerged. Fry until golden brown and drain on paper towels.

Finally, enjoy these wonderful croquettes.