Preheat oven to 350 F. Line a cookie sheet pan and set aside. Warm the butter so it's easy to cream. Either leave it at room temperature for a few hours or carefully microwave it until it is soft, not runny.
Measure the Flour
Measure the flour carefully. It must be exact or your cookies will be too dry or too wet. The best way to measure flour is to weigh it. To do this, first weigh your measuring cup without the flour.Then, loosen the flour in the flour bag with a spoon. Then carefully spoon the right amount into a 1 cup measuring cup (the metal ones I have linked to are perfect). Level off the top of the cup with a knife and then weigh the flour-filled cup. Remove or add flour with a spoon until the weight matches the need.I normally like to then add the measured flour to the mixing bowl by sifting it to inject air and fluffiness. To do this, either use a flour sifter, or just pour the flour into a fine-mesh sieve and use a spoon to work the flour through. At this point also add the baking soda and salt.
Make the Cookies
In one large mixing bowl, add the butter and cream until pasty. Then add the sugar, vanilla and milk. Hand mix with a spoon until combined.
Add the flour mixture to the batter, kneading with your hands until all ingredients are combined.
I wrap cookie dough in a piece of parchment, and freeze it for 15 minutes.Then I take it out, add another sheet of parchment paper on top and roll until it is about 1/2 inch thick.
Peel off the top parchment. Cut shapes. I used a round cutter. And peel away dough between the cut out shapes. Repeat until you have a parchment full of cut out shapes.
Bake them 9-11 minutes or until you see the cookie edges appear dry. You want the center to be soft; it will harden as the cookies cool.
Lift the parchment with the cookies on it onto a cookie sheet. I always use a 1/4 cookie sheet size for ease of handling. Freeze the cookies for 15 minutes before baking to ensure they don't puff up too much.
Bake for 10 minutes. Remove them and add the sparkling sugar at the point if you intend to. Let the cookies cool completely. Prior to dipping them into chocolate, put them in the freezer for 15-30 minutes.
Make the Dipping Sauce
Break up the bar, put the pieces and the tsp of coconut oil in a micro-wave safe bowl, and zap it for 60 seconds. Stir the melted chocolate until completely smooth.
Dip chilled cookies, and sprinkle immediately with the sparkling sugar. Store in a cool dry place in an air-tight container.