vanilla sandwich cookies with spiced rum filling 
recipe by & from

vanilla cookies
2 ¼ cups all-purpose flour
2 ts cornstarch
¼ ts baking powder
½ ts baking soda
½ ts salt
1 cup unsalted butter, room temp
¾ cup granulated sugar
2 egg yolks, room temp
2 ts pure vanilla extract

spiced rum filling
8 TB unsalted butter, room temp
1 cup + confectioners' sugar (might need a bit more)
giant pinch of salt
1 oversized Tablespoon of “Spiced Rum” (captain morgans has the best flavor)

Cook Notes: I’ve found the thinner you slice your cookie dough the crispier you can get your cookies. 
This will lend itself to an almost vanilla Oreo cookie-like texture. 
 Of course the thicker the cookie the less crunchy; so do what you feel is best.

In a large mixing bowl, whisk together the flour, cornstarch, baking powder, baking soda, and salt; set aside.
In the bowl of your stand mixer, fitted with the paddle attachment, beat the butter and sugar together on med-high until well mixed. 
Add in 2 egg yolks and vanilla extract and mix.
Scrape down the sides and bottom of the bowl.
Add the flour mixture and beat on low speed until just combined. Please do not overmix.
Scrape the cookie dough out onto a very lightly floured surface.
Form it into a two long logs. Wrap in plastic wrap, and refrigerator at least 2 hours or overnight. 
 I find that once the log is wrapped its easier to form it into a more even log by rolling it back and forth as if it were a rolling pin. 
 Get it as uniform as you can since we will be using this to slice out round cookies.
When ready to bake the cookies, preheat the oven to 350 degrees.
Line cookie sheets with parchment paper.
Remove one log of cookie dough from the fridge, place on lightly floured wooden board, and using a sharp knife slice cookies as thin as you can get them. 
Place on cookie sheet about two inches apart. 
If your cookies slices didn’t come out as thin or round as you like, then do what I did (see photo above) and roll into ball and gently press down into circle.
Bake the cookies for 9-10 minutes, or until they have puffed and the tops look set. 
Remove the sheets from the oven and allow the cookies to rest for about 8 minutes before transferring them to cooling rack. 
Cool completely before adding the filling.

For the filling: 
Using a hand mixer or stand mixer mix all ingredients until well combined.
Do a taste test and see if it needs more salt or rum. Chances are it won’t.
Using a plastic bag with edge snipped off or a pastry bag, place filling in bag and pipe onto cookies.
I don’t remember how many these made, sorry, but I think it was 20-25 sandwich cookies. I know there was enough filling for all.