1. Peel the carrots and potatoes.
2. Wash, dry, and grate them.
3. In a large skillet, heat the butter and add the vegetables, minced onion, salt, and pepper.
4. Cook gently for 15 minutes, stirring occasionally.
5. In a pitcher, mix the milk, eggs, and grated cheese.
6. Pour over the vegetables and cook over low heat for about 15 minutes.
7. Slide the galette onto a serving plate and serve it hot.