The cookies should just be pale golden brown on the bottom. The color and weight of the cookie sheet significantly influence cooking. I find that shiny aluminum cookie sheets of medium weight work best. Dark metal will cause the bottom of the cookies to brown too much. Allow the cookies to rest for about 30 seconds before removing them from the cookie sheets. If you wait too long the cookies will lose their flexibility and are likely to break.
Combine cinnamon and three tablespoons sugar. Reserve.
Grind the walnuts and reserve.
Put the butter in a mixing bowl and leave at room temperature for about 30 minutes to soften slightly.
Add 1 cup of sugar and flour to the butter.
Mix with a pastry blender until little beads form.
Add the cream and egg yolks and continue mixing with the pastry blender until a shaggy dough forms.
Press into a log, cut in half (or quarters) and wrap in plastic wrap and refrigerate for 30 minutes.
Roll a portion of dough between sheets of waxed paper to approximately 1/8 inch thick.
Cut into shapes.
Arrange on ungreased cookie sheets.
If the dough starts to warm too much it will be difficult to get the cookies off the waxed paper. If this happens, put the rolled out dough, still between the waxed paper, in the refrigerator for a few of minutes.
Brush with unbeaten egg whites.
Sprinkle with ground walnuts
Sprinkle with cinnamon sugar.
Bake 350°F approximately 8-9 minutes or until light brown on the bottom.
Remove from the cookie sheet almost immediately and cool on a wire rack.