HEAT olive oil in medium saucepan over medium heat. Add onion and cook until tender, about 5 minutes. Stir in flour; cook 1 minute. Stir in milk. Cook until sauce thickens, about 3 minutes, stirring constantly. Stir in cheese, jamon serrano, hot pepper sauce, salt and pepper. Spread mixture onto a dinner plate. Chill until firm.
BEAT eggs lightly in medium bowl. Place bread crumbs in another medium bowl. Shape ham mixture into 1-inch balls or 2-inch long ovals or cylinders. Dip each croquette in bread crumbs to coat. Roll in beaten egg, then return to bread crumbs and roll until coated on all sides. Chill 1 hour.
HEAT 3/4-inch vegetable oil to 350°F in medium heavy saucepan over medium-high heat. Cook croquettes in oil, a few at a time, until golden brown, about 3 minutes. Serve warm with marmalade.
Serving Size (1 croquette), Calories 180 (Calories from Fat 120), Total Fat 14g (Saturated Fat 3.5g, Trans Fat 0g), Cholesterol 45mg, Sodium 210mg, Total Carbohydrate 8g (Dietary Fiber 0g, Sugars 1g), Protein 6g; Percent Daily Value*: Vitamin A 2%, Vitamin C 4%, Calcium 8%, Iron 2%.
*Percent Daily Values are based on a 2,000 calorie diet.