Prepare two twelve-cup muffin tins by spraying with nonstick baking spray. Heat oven to 350 degrees F.

Add flour, salt and baking soda to a medium sized mixing bowl. Mix together and set aside.

Add brown sugar and egg to another bowl and using an electric hand mixer, cream the sugar and egg together. Add vanilla extract and continue mixing. Carefully add the melted Land O Lakes® Unsalted Butter to the bowl and mix again with the hand mixer. Add peanut butter and throughly combine with the hand mixer.

In two batches, add the flour mixture and combine with a rubber spatula, taking care to not over mix. Scoop cookie dough into the prepared muffin tins. Bake for 13 to 14 minutes, or until a toothpick inserted in the center of a couple of cookie cups comes out with crumbs.

Remove from the oven and place the muffin tins on a cooling rack. Allow to cool at least 15 minutes before removing.

Place chopped dark chocolate in a stainless steel mixing bowl.

Add butter to a saucepan. Turn the heat to low and allow the butter to melt. Once it’s melted, turn the heat to medium. Once the butter starts bubbling, allow it to bubble for about a minute (taking care so the butter does not brown). Pour the butter mixture over the chocolate in the bowl.

Allow the chocolate to sit for 5 minutes, without stirring. After waiting, stir with a rubber spatula until it’s thoroughly mixed together and all of the chocolate has melted. Allow it to cool completely and set, about 45 minutes.

Then, you’re ready to pipe it. Add to a frosting bag and using a 1M tip, pipe a swirl on each cookie cup.