Position rack in center of oven and preheat to 350 degrees F.

Combine flour, poppy seeds, and allspice in a bowl and set aside. Butter 2 heavy, large cookie sheets and set aside.

Using a vegetable peeler, remove all the zest from the orange (only remove the orange part, not the bitter white pith). Save orange for another use. Place the granulated sugar and zest in a food processor. Process until peel is finely minced, about 2 minutes. Transfer the sugar-zest mixture to an electric mixer. Add 1 cup butter and beat until light and fluffy. Beat in egg yolks. Add the flour mixture and mix slowly until combined into a soft dough.

Using a small cookie scoop, place 1-inch high mounds 2 inches apart on cookie sheets and press cookie down using a spatula dipped in water.

Bake until edges are light brown, about 10 to 12 minutes. Cool on wire racks. Make the glaze by combining the powdered sugar and cream in a bowl. Using a pastry brush, brush the glaze over the cookies and then sprinkle with poppy seeds. Let stand until glaze is hardened and not wet. Store in an airtight container.