Preheat oven to 375 degrees Fahrenheit and prepare a baking sheet with either parchment paper or a silicon baking mat.

In the bowl of a stand mixer or mixing bowl, beat softened butter, sugars, and vanilla extract until it is light and fluffy (pictured in images above). This should take 5-10 minutes.

Scrape down the sides of the bowl and add the sourdough discard and eggs. Mix until just combined.

In a separate bowl, whisk together the flour, cinnamon, nutmeg, baking soda, salt, and quick-oats.

Slowly add the dry ingredients to the wet ingredients and mix until combined.

Using a cookie scoop or spoon, place dough balls 2 inches apart on the prepared cookie sheet. With a fork, lightly flatten the cookies to allow for more even baking. This step is optional but recommended for consistency.

Place in oven and bake for 8 minutes. Remove from the oven and allow the cookies to cool on the pan for at least 5 minutes before transferring the cookies to a cooling rack.

Allow to fully cool before adding the maple glaze.

After the cookies have fully cooled, add the powdered sugar, maple syrup, cinnamon, and vanilla and whisk until fully combined. If the glaze is too thick, add in your milk of choice 1 teaspoon at a time until it is runny enough to drizzle from a spoon.

Once combined, use a spoon to lightly drizzle the glaze over the cooled cookies. Alternatively, you could dunk the top or one side of the cookie into the glaze (this is easier AND you get more glaze per cookie-- win/win!)

Place glazed cookies on a rack or parchment paper until the glaze has fully dried and set.