Cream the butter and sugars: Using a hand mixer or a stand mixer fitted with a paddle attachment, cream the butter, cane sugar, dark brown sugar, molasses, and vanilla extract. Mix on low until combined, then speed mixer up to medium and continue to cream the butter mixture for 5 minutes, until it is noticeably lighter in color.
Make the dough: Add the sourdough discard, flour, Chinese five spice, baking soda, and salt in that order. Mix on low until combined into a stiff dough.
Prep: Line one baking sheet with parchment paper. Pour the cane sugar for the topping into a bowl. Set aside.
Portion out your cookie dough: Using your hands, or a 1 ½ tablespoon cookie scoop, form or scoop the dough into 22 balls and roll them in the cane sugar. Place on the prepared baking sheet.
Chill dough: Refrigerate the baking sheet for at least 1 hour, or you can refrigerate overnight.
Prepare for baking: Preheat the oven to 375°F. Line another baking sheet with parchment paper. Transfer half the cookie dough balls onto the second baking sheet, and space them all at least 1-inch apart.
Bake: Bake for 10 to 12 minutes, or until the cookies look puffed and dry around the edges. Allow to cool completely on the baking sheets.
Enjoy and store: These cookies are best enjoyed once they are fully cooled and are even better a few days after being baked. Store in an airtight container for up to 7 days.
High Altitude: Bake at 375°F for 8 to 10 minutes, or until the cookies look puffed and dry around the edges.