Gratin of Leeks and Turnips – French Women Don't Get Fat

Ingredients

• 2 lbs leeks, cleaned, washed and cut into 3 inch pieces
• 1 lb turnips, washed and cut into 2 inch pieces
• 2 eggs
• 1 tablespoon Dijon mustard
• 4 tablespoons sour cream
• 1/4 cup walnuts, finely chopped
• 3 oz grated cheese (parmesan, gruyere, comté or emmental)
• 1/2 teaspoon butter
• Salt and freshly ground pepper