Cook fettuccine according to package directions. Drain. Meanwhile, in a medium saucepan cook onion and garlic in hot margarine or butter until tender but not brown. Stir in flour, fresh dill or dillweed, salt, and pepper. Add milk all at once. Cook and stir until thickened and bubbly. Remove from heat. Stir in baby food carrots and cooked fettuccine.
In a medium bowl, beat egg yolks with a fork until combined. Gradually add carrot mixture, stirring constantly. Set aside.
In a large bowl beat egg whites until stiff peaks form (tips stand straight). Gently fold about 1 cup of the beaten egg whites into the carrot mixture.
Gradually pour carrot mixture over remaining egg whites, folding to combine. Pour into an ungreased 1-1/2-quart souffle dish or a 2-quart square baking dish.
Bake, uncovered, in a 350 degree F oven for 35 to 40 minutes or until a knife inserted near the center comes out clean. Serve immediately. Makes 4 servings.