Shortbread Dough. In a large mixing bowl beat together your butter and powdered sugar until fluffy (about seven minutes) stopping to scrape down the sides occasionally. Then scrape down the sides of the bowl and add your flour and then mix the ingredients until combined.
Refrigerate. Transfer your cookie dough to a piece of parchment or wax paper. Shape the dough into a square and then wrap the dough in plastic wrap and refrigerate for at least an hour.
Bake. Preheat your oven to 350 and prep a rimmed baking sheet (or two) for nonstick. Parchment paper or a baking mat can work. Roll the cookie dough out to a half inch thickness and use a round cookie cutter to cut the cookies out. Place the cookies about an inch apart on the baking sheet and bake for 12 to 14 minutes or until the cookies begin to brown around the edges. Allow the cookies to fully cool.
Peanut Butter Filling. Beat together the peanut butter, powdered sugar, and vanilla until creamy. Then carefully place a dollop on top of each cookie and spread it over the top of the cookie (thicker on top and tapered to the sides of the cookies).
Chocolate. In a large microwave-safe bowl, melt together the chocolate and coconut oil, stopping to stir every 30 seconds.
Coat. Line a rimmed baking sheet with wax or parchment paper. Then use a fork or a spoon to dip each cookie into the melted chocolate and then place it onto the baking sheet to set.
Set. Transfer the baking sheet to your refrigerator and refrigerate until fully set.