Onion Soup with Puff Pastry
Peel and slice onions. Heat butter in a pan and cook onions for about 10 minutes. Deglaze with white wine and season with salt, pepper and thyme.
Preheat the oven to 200°C (400°F). Add broth to onion stock, bring to a boil and simmer for 5 minutes.
Cut puff pastry in half and roll out onto a lightly floured surface. Season onion soup to taste and ladle into ovenproof soup tureens.
Sprinkle cheese over soup. Cover each terrine with puff pastry, trimming te excess. Whisk egg yolk with 1 tablespoon water and brush onto the pastry.
Bake soup tureens until pastry is golden, about 15 minutes. Serve immediately.