Beat butter or margarine in a mixing bowl with an electric mixer on medium speed for 30 seconds.
Add 1 cup sugar, cinnamon, baking soda, and ¼ teaspoon salt; beat until combined.
Beat in molasses and eggs until combined.
Beat in as much flour as you can. Stir in remaining flour. Divide dough in half; cover and chill until easy to handle.
Meanwhile, for filling, combine the egg yolks, lemon juice, ⅛ teaspoon salt, and 1 tablespoon. water in a small saucepan.
Cook and stir over medium heat until thickened and bubbly. Cook and stir 1 minute more.
Stir in coconut and lemon peel. Cool.
Roll each portion of dough on a lightly floured surface into a 15 x 6-inch rectangle.
Spread one fourth of the filling in a 1-inch-wide strip lengthwise down center of each rectangle.
Fold each long side of dough over filing, overlapping slightly in center; seal.
Place seam-side down on working surface.
Cut crosswise into 1½-inch bars. Place bars 1½ inch apart on ungreased cookie sheets.
Bake in a 350℉ (180℃) oven about 12 minutes or until set.
Cool cookies on wire racks.
If desired, drizzle with melted candy coating.