1 (15 ounce) can sweet potatoes, drained
1/2 cup butter
1 (8 ounce) can diced carrots
1/4 teaspoon salt
1/4 teaspoon ground black pepper
2 large egg whites
1 cup white sugar
1/4 cup milk
2 teaspoons lemon zest
Preheat oven to 350 degrees F (175 degrees C). Lightly grease a 9x13 inch baking dish.
In a large saucepan, melt butter and butter. Stir in carrots and salt. Stirring constantly, combine egg whites and sugar. Gradually mix into the butter mixture, stirring constantly.
Slowly pour milk into the saucepan. Stirring constantly, pour lemon zest into the milk. Bring to a boil, then stir in sweet potato, carrots and salt. Sprinkle mixture over the casserole.
Bake uncovered in the preheated oven for 1 hour, or until bubbly and golden brown. Serve hot.