Please read about Deep-Frying.

Melt in a medium saucepan over medium heat:

Gradually stir in, then cook for 2 minutes, stirring constantly:

Whisk in and cook, whisking frequently, until very thick, about 5 minutes:

Reduce the heat to low and stir in:

Remove from the heat and stir in until blended:

Spread the mixture in a well-oiled 8-inch square baking dish. Cover and chill until firm, about 1 hour in the freezer or 2 to 3 hours in the refrigerator.

Turn the mixture out onto a work surface and cut into 2-inch squares.

Heat to 365°F in a deep-fryer, deep heavy pot, or Dutch oven:

While the oil heats, flour your hands and dredge the croquettes in:

Let the croquettes dry on a rack for 10 minutes, then coat with the flour again. Fry the croquettes in batches until golden, 2 to 4 minutes. Drain on paper towels and serve with: