Make the Cookie Dough

• Line 2 baking sheets with parchment paper. Sift together 7 ½ oz all purpose flour, 1 teaspoon baking soda, 1 teaspoon cinnamon and ½ teaspoon salt onto one of the parchment sheets, set aside
• Cream 8 oz unsalted butter, 8 oz light brown sugar and 4 oz granulated sugar on medium speed for about 2-3 minutes. Scrape the bowl. Add 2 large eggs and 2 teaspoons vanilla extract and mix just until combined, scrape the bowl. With the mixer running on low speed, add 8 oz sourdough discard.
• Use the parchment sheet to lift and pour the flour mixture into the bowl. Mix until half way combined. Add 10 oz old-fashioned rolled oats all at once and mix to combine. You may need to finish the dough off the mixer to incorporate the oats evenly.
• Using a 1.5 oz cookie scoop or spoon, scoop the dough into 1.5" balls. Set the cookies onto one of the prepared baking sheets with the dough balls almost touching. Refrigerate the cookies for 30-60 minutes until the dough balls are firm to the touch. (See note)
• While the cookie dough is chilling, make the glaze. Combine 8 oz confectioner's sugar and 2 oz fresh lemon juice in a small bowl and stir until the glaze is smooth. Preheat oven to 375 °F.
• Transfer 15 of the dough balls to the other prepared baking sheet. At this point you can freeze the rest of the dough balls to bake later or return them to the refrigerator while the first tray bakes. Bake the cookies until golden brown around the edges and the center is just barely set, about 10-12 minutes.
• Allow the cookies to cool just long enough that you can pick them up without breaking. Spread the glaze onto the cookies while they're still slightly warm. The glaze will set as the cookies finish cooling.