Rinse the millet under cold water. In a saucepan, combine the millet, milk, water, and 1/2 tsp of salt. Bring to a boil, then reduce heat, cover, and simmer until the liquid is absorbed and millet is tender, about 20-25 minutes. Remove from heat and let it sit, covered, for 5 minutes.

Meanwhile, cut the chicken thighs into bite-sized pieces. Heat butter or oil in a large pan over medium-high heat. Add chicken and cook until browned and cooked through, about 6-8 minutes. Remove chicken from the pan and set aside.

In the same pan, add the chopped onion (if using) and sauté until softened, about 3-4 minutes. Add the grated carrots and sliced cabbage. Cook, stirring occasionally, until the vegetables are tender-crisp, about 8-10 minutes.

Preheat your oven to 180°C (350°F). In a large bowl, whisk together the eggs, varškė (curd cheese), and the remaining 1/2 tsp of salt.

Add the cooked millet, cooked chicken, sautéed vegetables, and diced tomato to the bowl with the egg mixture. Gently stir everything together until well combined.

Pour the mixture into a large oven-safe baking dish. Sprinkle the grated cheese evenly over the top.

Bake for 25-30 minutes, or until the cheese is melted and bubbly and the top is golden brown. If using, sprinkle with fresh herbs before serving.