Boil all vegetables in salted water or steam until crisp and rinse in ice water until cold.
Meanwhile, sauté the very finely chopped onion at low temperature in a little olive oil.
Add the millet, sauté briefly and deglaze with the stock. Cook gently for 20 minutes, stirring frequently. Let it cool down a bit.
Mix the millet with egg, cream, milk and spices. Spread the gratin mixture over the vegetables, sprinkle with Grana Padano and bake in the oven at 200 °C for about 8-10 minutes until golden brown.
Garnish with fresh herbs.
Serve the chive yogurt separately.