Add softened butter and confectioner's sugar to a large bowl. Whisk until light and fluffy.There is also no over beating at this point! This is when you want to really go for it. Whisk until as light as possible. You won't be able to get them as fluffy as you would with cookie recipes that don't have peanut butter in them. But airiness during this step is absolutely essential. When you think that you've whisked them enough, whisk a little bit longer!
Add the egg and mix until just barely incorporated.Do not over beat! It's better to have the egg not incorporated enough than too much. You just don't want the egg to be liquid on top.
Whisk in the salt, Spekulatius spice blend, and flour until barely incorporated.This is the exact opposite of the butter mixing process! When you add flour, over mixing will make thee cookies dense and texturally unpleasant. In order to keep the airiness, mix as little as possible to stop seeing white pockets of flour.
Chill
Wrap in plastic wrap and chill for 30 minutes.
Cook
Preheat oven to 400 degrees Fahrenheit.
On a lightly floured surface, roll out the dough until 1/4 inch thick.It can help to do this on top of waxed or parchment paper as well. This can help keep it from sticking to the countertop or to use less flour.
Roll over once more with the embossed rolling pin to imprint the pattern.
Cut out with cookie cutters and place 2 inches apart on a baking sheet.
Bake for 7-8 minutes, or until just barely golden brown.
Move cookies from the baking sheet and place on a cooling rack or in the refrigerator to set completely.
Tips, Tricks, & Notes
For more information on the Fundamentals of Baking Cookies, check out my article on the matter. For instance, I recommend making cookies by hand with a fork and adding slightly less flour than called for.