For the cookie:
1. Preheat oven to 350°.
2. Line baking sheets with parchment paper and set aside.
3. In the bowl of your stand mixer, cream butter and sugar together until smooth.
4. Add in egg and vanilla and mix until smooth.
5. Incorporate all dry ingredients and mix on low speed until just combined.
6. Take dough out of bowl and knead it a little bit to gather into a ball.
7. Roll out on a floured surface under a piece of parchment or wax paper until it's about 1/4 - 1/8in thick.
8. Cut out your selected shapes and place on prepared baking sheet. You can place them close together because they pretty much hold their shape.
9. Bake for 12-14 minutes depending on how crunchy or soft you want your cookies to be.
When done, let them completely cool on the baking sheet.
For the Cream Filling:
1. In the bowl of your stand mixer, cream butter and shortening together.
2. Add in half of the confectioner's sugar and mix on LOW (or else it will be snowing sugar in your kitchen) until combined.
3. Add in vanilla and cream.
4. Pour in the second half of the confectioners sugar and mix on low again. It may seem a little crumbly, but keep mixing and it will come together. About 2 minutes.
5. When it is ready, you should be able to pull it apart and mold it with your fingers.
6. Start spreading some on your cookies and sandwiching them together.
7. Next step: Eat them up! Enjoy :)