1ounce (28 g)finely grated cocoa butter (grated on a micro plane grater)(the same amount of canola, vegetable, or melted coconut oil may be substituted)
Make the Cookies:
Beat butter until smooth. Add powdered sugar and continue beating until incorporated. Add egg white and vanilla extract and mix well to combine.
In another bowl, combine all dry ingredients. Add dry ingredients to butter and egg mixture and mix on low until combined. Form the dough into a disk, wrap it in plastic wrap, and chill until cold, about one hour.
Preheat oven to 350° F. Line a baking sheet with parchment paper and set aside.
Roll chilled dough to ¼-inch thick and cut with a small round cookie cutter or biscuit cutter (I used a 1¾-inch, but a 2-inch will also work). Place on parchment-lined baking sheet. Using a melon baller (or something similar, such as a teaspoon measure) make an indentation into the middle of each cookie.
Bake cookies for 10-12 minutes, or until the bottom edges are just brown. This next step is optional, but replaces a dehydrator if you want to make the cookies extra crisp. Reduce the oven temperature to 170° F and bake for an additional 45 minutes. Cool completely on wire racks.
Make Peanut Butter Filling
In a large bowl, combine all filling ingredients and beat until smooth.
Spread about 1 tablespoon of filling over the entire surface of each cookie. Place cookie filling side down on parchment-lined baking sheet, pressing very gently. Refrigerate cookies until filling is firm. This will set the filling and when the cookies are peeled off the parchment, the tops will be flat and smooth.
In a large microwavable bowl, microwave the chocolate on half power in 30 second intervals, stirring between each, until melted. Add fat of choice and stir until completely smooth and melted.
Dip Cookies in Chocolate
Set up dipping station by placing chilled cookies on the left, melted chocolate in the middle, and a waxed or parchment-paper lined baking sheet on the right. Using a dipping fork (or regular fork), dip cookies in chocolate and tap on side of bowl to remove excess chocolate. Place edge of fork on empty sheet tray and gently slide cookie off fork and onto sheet tray.
Allow chocolate to set at room temperature, or chill them until chocolate is set. Cookies will keep in a covered container at room temperature for about 3-4 days, refrigerated for about a week, or frozen for up to 3 months.