Cut butter into flour as for pie crust.
Combine egg yolk and cream. Add to flour. Mix until well blended.
Form into a ball and wrap in plastic wrap or waxed paper. Chill several hours or overnight.
Preheat oven to 375 degrees.
Divide dough into four portions. Roll each portion into a circle about 12 inches in diameter.
Cut each circle into 16 wedges.
Put filling on top and roll up starting from the outside rolling toward the center.
Bake on ungreased cookie sheet for 20 minutes or until delicately browned.
Sprinkle with powdered sugar while warm.