1/2 cup butter, softened
1/3 cup brown sugar
1 teaspoon lemon zest
1 teaspoon ground cinnamon
3 egg yolks, beaten
2 cups rolled oats
2 tablespoons lemon juice
Preheat oven to 325 degrees F (165 degrees C). Grease cookie sheets.
In a medium bowl, cream together the margarine, brown sugar, lemon zest and cinnamon. Beat in the egg yolk alternately with the flour, ending with the flour. Mix just until incorporated. Drop by rounded spoonfuls onto the prepared cookie sheet.
Bake for 8 to 9 minutes in the preheated oven. Allow cookies to cool on baking sheet for 5 minutes. Remove from cookie sheets to a wire rack to cool completely.