To make the cookies:
1. In the bowl of an electric mixer set on low, combing all the cookie ingredients. Once combined, the dough will seem "sandy" or granular from the sugar. This will decrease during the chilling time as the sugar crystals will dissolve.
2. Use a medium (or 2 T) cookie scoop to scoop mounds onto a large plate or cookie sheet. Cover with plastic wrap and chill in the fridge for 3 hours, up to 5 days.
3. 20 minutes before baking. Preheat the oven to 350 degrees F.
4. Line cookie sheets with parchment paper or silicone mats. Place chilled cookie dough mounds 2 inches apart on the cookie sheet and use a fork to press on the dough to make a crisscross pattern.
5. Bake for 8 minutes, or until the edges of the cookies are set. The center of the cookie might seem under baked, but the cookies will firm as they cool.
6. Allow cookies to cool completely on the cookie sheet before removing.
While cookies are baking, make your chocolate ganache:
1. Pour the chocolate chips into a bowl.
2. Heat the cream on the stove or in a microwave safe dish until simmering.
3. Pour the cream over the chocolate and allow to rest for 2 minutes before stirring.
4. Stir the cream and chocolate chips, starting in the center of the bowl and working outwards as the mixture comes together into chocolate ganache.
While the cookies are cooling, make your peanut butter filling:
1. In the bowl of an electric mixer, beat the butter and peanut butter together on medium speed until smooth. Turn the mixer off and add the powdered sugar and vanilla extract. When turning the mixer back on, start on very slow speed and work your way up to medium to avoid powdered sugar spilling out of the bowl. Mix until smooth. Add milk, and mix well to combine. If you feel your filling is too thick at this point, add a splash more of milk until you reach your desired consistency.
Sandwich your cookies!!
1. Using a piping bag, or a plastic freezer bag with the corner cut, pipe the peanut butter filling onto the flat side of a cookie to cover the surface.
2. Spoon or pipe a dollop of chocolate ganache on top of the peanut butter frosting.
3. Gently sandwich with another cookie.
These cookies taste great at room temperature or just out of the fridge. I store the cookie sandwiches in the refrigerator for up to 5 days.