Prepare basic shortbread, and roll into 1-inch balls; refrigerate 20 minutes. Bake on a cookie sheet until firm and just starting to color, 20 to 25 minutes. Let cool completely on a wire rack.
Make glaze: Whisk together confectioners' sugar, cream, and lemon juice until well combined and smooth. Stir in poppy seeds. Dip top half of cooled shortbread balls into glaze, allowing excess to drip off. Transfer to a parchment-lined baking sheet to set.
If not using the glaze immediately, refrigerate, tightly covered, up to two days; bring to room temperature before using.