Clean the onion and chop it finely. Also clean the broccoli and cut it into florets.
Cut the Fontina AOC into cubes by removing the rind and keep it aside.
In a cast iron pan, add a little olive oil and sauté the onion. Add the broccoli florets and cook for a few minutes. Add half a glass of water and leave to soften for 10 minutes. Season with salt and pepper. Add the crumbled sausage and cook over a high heat.
Transfer the mixture into a bowl and keep the cast-iron pan aside.
In a bowl, combine the two eggs, fresh cream, diced Fontina AOC and fresh thyme. Season with salt and pepper and mix well.
Spread the brisè pastry on the bottom of the still-oiled pan and pour the broccoli with the sausage into the centre and top with the egg mixture.
Close the edges of the pastry, brush them with beaten egg yolk and a little milk and bake in a preheated oven at 180° for 20 minutes.