Baked Zucchini Squash

6 sm. or 4 med. zucchini
1/2 c. sour cream
1 T. butter
1 egg yolk
1 T. Parmesan cheese
2 T. chopped chives

Dice zucchini and boil in salted water 6 to 8 minutes. Drain well. Melt butter and cheese over low heat, add sour cream and blend well. Remove from heat and add egg yolk and chives. Put zucchini in buttered casserole, pour sauce over and mix well. Bake at 350 degrees for 25 to 30 minutes. Serves 6.