Use a hand mixer or the bowl of a stand mixer fitted with the paddle attachment. Beat the softened butter, dark brown sugar, and molasses until smooth and fluffy on medium speed.
Add the wet ingredients.
Mix in the egg, vanilla extract, and sourdough discard.
Whisk the dry ingredients in a separate bowl.
Combine flour, baking soda, salt, and warm spices.
Combine wet and dry.
Add the dry ingredients to the butter mixture on low speed until a sticky dough forms.
Choose your fermentation option:
Rest 1 hour minimum (quick bake)
Short ferment: Cover dough with plastic wrap and let rest 4-6 hours at room temperature
Long ferment: Refrigerate covered 12–48 hours for best flavor and thickest cookies
Bake.
Preheat oven to 375 degrees F. Scoop dough using a cookie scoop onto a prepared baking sheet lined with parchment. Roll in sugar if desired. Bake cookies 10–12 minutes until edges are set. Transfer to a cooling rack.
Notes
Storage, Freezing, and Make-Ahead Tips
Room temperature: Store in an airtight container for up to 5 days.
Freeze baked cookies: Freeze in a sealed bag with pieces of parchment between layers.
Freeze dough: Scoop dough balls and freeze, then bake from frozen, add 1–2 minutes bake time.
Leftover cookies: Perfect for gifting to family members or adding to cookie boxes.