Separate the chard leaves from the stem and use them elsewhere.
Remove the wires from the stems. Wash the stems and cut into 4-5 cm long pieces. Cook in boiling salted water for 15-20 minutes, drain off the water.
Beat eggs with crème fraîche and cheese. Salt and pepper. Butter the gratin dish, layer in the chard and cover with the egg mixture. Bake in the oven preheated to 200 degrees for 20 minutes. To get a browned crust, brown it under the grill for 3 minutes.