Cut 3-4 merguez sausages into bite-size pieces, about 2.5cm - 3cm (1" - 1½") long . Heat a frying pan, add a little olive oil, and place your merguez sausages pieces into the pan. Merguez are made of beef meat and/or lamb and are spicy enough, so just add a little touch of salt and freshly-ground black pepper. When the sausages start releasing the fat, add 2 cloves of finely chopped garlic. Spread the garlic across the pan.
The merguez will cook in just a few minutes. Meanwhile, take 60g (2oz - or one large handful) of fresh parsley and roughly chop it. Add your parsley just before taking the pan off the heat. Then, add 60g (2oz) of capers (drained and washed). Stir well, until everything is heated through, then remove from the heat. Place the mixture in a bowl using a slotted spoon.
Slice the lids off the croissants and set them to one side. Dunk each croissant (cut side down) into the juices that remain in the pan. Leave them in the hot pan for a moment to allow them to caramelize, then remove from the heat. Push your thumbs inside each croissant to create a little pocket for the merguez and parsley stuffing, then heap the stuffing into the croissants.
Slice fontina cheese really thin (preferably using a cheese slicer). Place two or three slices over the the sausage stuffing in each croissant. Season with a touch of pepper. Place the stuffed croissants (still without their lids) onto a baking tray and place under a preheated grill (broiler) for 30-45 seconds until the cheese has just melted. Replace the lids of the croissants and enjoy with family or friends.