Split leeks lengthwise and wash thoroughly under cold water. Shake dry and slice thinly.
Sauté leeks with sausage until tender. Remove from heat and mix in half the cheese. Spoon into pastry shell.
Beat eggs until blended, mix in cream, salt, pepper, and nutmeg. Pour over leek and sausage mixture. Sprinkle with remaining cheese. Dot with butter. Bake at 375 degrees for 35 minutes or until set and slightly puffed.
Rest 15 minutes before cutting.