Preheat your oven to 350°F. Mix all the shortbread cookie ingredients in a large bowl until a dough forms.
Using a small cookie scoop or rolling them into balls, place them on a parchment-lined baking sheet. Flatten them slightly with your palm and make a small indent in the center of each one.
Bake for 9-12 minutes until golden around the edges. Let them cool completely; you can speed up the process by placing them in the freezer.
Mix all the peanut butter filling ingredients in a small bowl until smooth. Once the cookies are cool, fill the indents with the peanut butter mixture.
Return the baking sheet to the freezer to firm up the filling before dipping them in chocolate.
Melt the chocolate and coconut oil together using either a double boiler or in the microwave in 30-second increments until smooth.
Quickly dip each cookie in the chocolate, letting any excess drip off by running a fork along the top side of the bowl.
Place the dipped cookies back on the sheet. Sprinkle a bit of flakey sea salt on top if desired. Freeze for about 20 minutes until the chocolate hardens.
Once set, store the cookies in an airtight container in the fridge or freezer.
