Cut the onions into thin slices, divide into rings.
2 tablespoon. Melt the butter, sauté the onion until translucent, season with salt and pepper and a few thyme leaves.
Divide the onion rings into 4 ovenproof molds. Whisk the cream with the eggs, season with salt.
Grate the cheese, cut off the rind from 4 slices of toasted bread and cut the bread into small cubes, add to the cream with the cheese, distribute everything on the onions.
2 tablespoon. Place the butter in flakes on the bread cubes, slide the molds onto the wire rack in the oven.
Fan 180 degrees, not preheated, bake for approx. 20-30.