Authentic Belgian kaaskroketten: crispy golden breadcrumb croquettes filled with molten, creamy Belgian Trappist Chimay and Gruyère cheese roux, fried crisp with fried parsley and lemon.
Melt butter, whisk in flour for 1 minute, and gradually add milk to form a very thick white sauce. Beat in the egg yolks off heat, then fold in both cheeses, nutmeg, cayenne, salt, and pepper until smooth and molten.
Spread the cheese mixture in a buttered baking dish, cover with plastic film, and chill for at least 4 hours until completely firm.
Cut into squares or roll into cylinders. Dust with flour, coat in beaten egg, and roll in breadcrumbs, repeating the egg and breadcrumbs for an airtight seal.
Deep fry at 180°C for 3 to 4 minutes until deeply golden. Drain on paper towels and serve with flash-fried crispy parsley sprigs and lemon wedges.