Soft, chewy gingerbread cookies enriched with sourdough starter for a deep, nostalgic flavor, warmly spiced with ginger, cinnamon, cloves, and allspice. Perfect for decorating into festive shapes with a quick-setting royal icing.
In a large bowl or stand mixer fitted with the paddle, beat butter, brown sugar, and molasses on medium speed until creamy.
Add the egg, sourdough starter, and vanilla; mix on medium until incorporated.
In a separate bowl, whisk together flour, salt, baking soda, cinnamon, ginger, cloves, and allspice.
Add the dry ingredients to the wet ingredients and beat on low speed just until combined.
Divide dough in half, shape into two discs, wrap, and refrigerate for at least 1 hour or up to 3 days.
When ready to bake, let one disc sit at room temperature for a few minutes to soften slightly.
Preheat oven to 350°F (175°C). Line two large baking sheets with parchment paper.
On a lightly floured surface, roll dough to 1/4-inch thickness.
Cut into desired shapes and place 1 inch apart on prepared baking sheets. Repeat with the second disc, chilling scraps as needed.
Bake for about 10 minutes, until edges are set and lightly golden. For crisper cookies, bake a bit longer.
Cool cookies completely on the sheets or a rack, about 30 minutes, before decorating.
Make the royal icing: In a stand mixer with the whisk attachment, beat powdered sugar, room-temperature water, and meringue powder on high speed for about 2 minutes until thick and glossy; add more powdered sugar if needed to stiffen.
Decorate cookies as desired. Royal icing will typically dry within a couple of hours.