Cream butter + sugar until light and fluffy. Scrape down the sides of the bowl as necessary. Be sure to get any butter off the bottom of the bowl to incorporate.

Then add 2 eggs and 2 teaspoons of vanilla extract to the butter mixture and beat until well combined.

Mix in 1 cup of sourdough discard until fully incorporated.

In a separate, medium bowl, sift together 4 ¼ cups flour, 1 teaspoon of baking powder, and ½ teaspoon of salt. Then add the flour mixture to the bowl of wet ingredients and mix on low until everything is combined. Scrape down the sides and bottom of the bowl to get everything incorporated.

Shape the dough into a flat disk and wrap tightly in plastic wrap. Chill for 2 hours or up to 3-4 days in the refrigerator.

When ready to bake, preheat oven to 375°F.

Remove the dough from the fridge and let it sit on the counter for 10 minutes to soften slightly.

On a lightly floured surface, roll out the cookie dough to 1/4-inch thick. Cut out using cookie cutters and bake on a baking sheet lined with parchment paper for 10 to 12 minutes, rotating the baking sheet halfway through. The cookies will puff up in the oven, then settle down again and the edges will just barely start to turn golden brown when ready to be taken out.

Cool completely before decorating with sugar cookie frosting or royal icing.