Make the Cookies

1. In a bowl combine the flour, oats, baking soda, cinnamon, nutmeg and salt.
2. In the bowl of a stand mixer combine the butter, sugars and molasses. Mix on medium to high speed until light and fluffy, 4-5 minutes.
3. Add the egg, egg yolk, sourdough discard and vanilla, mix until combined.
4. With the mixer on low speed, gradually add in the flour mixture and mix just until combined. Cover and refrigerate for 30 minutes.
5. Using a 1½-tablespoon scoop, scoop the dough (32 g each) onto parchment-lined sheets. Cover tightly and refrigerate overnight.
6. Preheat the oven to 350°F. Space the chilled rounds about 2 inches apart on the lined sheets.
7. Bake one sheet at a time for 10-11 minutes until the cookie edges are set and the centers puff up but still appear slightly underdone.
8. As soon as the cookies come out of the oven, set a round biscuit cutter slightly wider than a cookie over one and swirl it in small circles until the edges pull into a neat round. Repeat with the rest, working quickly while they’re still hot and soft. Let cool on the cookie sheet for a few minutes, then transfer to a wire rack to continue to cool.

Make the Vanilla Cream Filling

9. In the bowl of a stand mixer beat the butter on high speed until creamy, about 1 minute.
10. Add the powdered sugar and beat on medium speed for 1-2 minutes.
11. Pour in the heavy cream, vanilla and a pinch of salt,  beat on high speed for 2-3 minutes. If the filling is too thick, beat in another tablespoon of cream.

To Assemble

12. Pipe or spread the filling on the bottom of half of the cookies. Top with another cookie and lightly press them together.