In a large bowl, cream butter and brown sugar until light and fluffy, 5-7 minutes. Beat in egg and molasses. In another bowl, whisk flour, baking soda, salt and spices; gradually beat into creamed mixture. Divide dough in half; shape each into a disk. Cover and refrigerate until firm enough to roll, 4 hours or overnight.
Preheat oven to 350°. On a lightly floured surface, roll each portion of dough to 1/8-in. thickness. Cut with a floured 3-1/2-in. sock monkey-shaped cookie cutter. Place 2 in. apart on ungreased baking sheets.
Bake until edges are firm, 8-10 minutes. Remove to wire racks; cool completely.
Place first 5 icing ingredients in a small bowl; beat on low speed just until blended. Beat on high until stiff peaks form, 4-5 minutes. Thin with cream to desired consistency. Divide icing into thirds. Tint 1 portion red and 1 portion gray; leave remaining portion white.
Pipe icing onto cookies and decorate with black sprinkles as desired. (Keep unused icing covered at all times with a damp cloth. If necessary, beat again on high speed to restore texture.) Let cookies stand at room temperature several hours or until frosting is dry and firm. Store in an airtight container.
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