Cut butter into flour. Add egg and sour cream; mix well. Shape into ball. Sprinkle with flour; wrap and chill over night. Divide dough into 4 parts. Roll 1 part on well floured board into an 8 inch circle. Cut into 8 wedges. Fill (use about 1 teaspoon) and roll up from wide end. Roll out remaining 3 parts the same way. Bake on greased cookie sheet for 25 minutes at 375 degrees.

When cool, sprinkle with powdered sugar. Makes 32 cookies.