Preheat the oven to 350 degrees F.
To make the cookies, in a medium-size bowl, combine the flour, confectioners’ sugar, butter, lemon extract, and lemon rind. Mix well.
Roll the dough into 1-inch balls. Place the cookies 1 inch apart on cookie sheets lined with parchment paper. With your thumb, make an imprint in the center of each cookie.
Bake for 8 to 10 minutes, or until lightly browned. Remove from the sheets and cool on wire racks.
To make the frosting, in a medium-size bowl, beat together the confectioners’ sugar, butter, lemon juice, and enough food coloring to make the frosting pale yellow. When the cookies are cool, place a dollop of frosting in the center of each one.