Spread the puff pastry on the floured worktop to a thickness of 3 mm. Cut out 4 squares of about 15 cm each, place on a baking tray covered with baking paper and keep in a cool place. Cut the goat's cheese into slices.
Brown the sliced onions for 20 minutes in a frying pan in hot butter over a low heat. Add 10 cl of water and the diced anchovies. Add a little salt and pepper. Continue cooking for 5 minutes.
Spread the onion fondue on the pastry squares, spread goat cheese slices on top and season with pepper. Bake 15 to 20 minutes in a preheated oven at 200°C. Serve hot.
Tip: Sprinkle the onion fondue with a pinch of cumin seeds while cooking.
A good salad: lamb's lettuce and strips of treviso leaves, seasoned with a vinaigrette of olive oil and freshly squeezed orange juice.