Clean the leek, halve lengthwise, wash and cut into fine strips. Heat the oil in a pan and fry the minced meat until crumbly. Add leek, steam briefly and season with salt and pepper. Add white wine, stock and cream, bring to the boil and simmer for about 2 minutes. Add processed cheese and sauce thickener and continue cooking for 1-2 minutes while stirring until the cheese has melted. Season to taste with salt and pepper