Put the butter in the bowl of a stand mixer. Using the whisk attachment, beat for about 3 minutes or until light and fluffy. Reduce speed to medium low. Beat in the salt and vanilla, then beat in both sugars, scraping the sides of the bowl often.

Add flour about ⅔ cup at a time. Stir by hand, or switch to the paddle and beat on medium speed until you have a cohesive dough. It will seem quite dry at first, but will all come together.

Shape dough into two large balls. Put each ball in a gallon size freezer bag. Flatten inside the bag, then roll to about ¼ inch. Repeat with second bag and put both bags of rolled dough in the refrigerator. Chill for one hour or until very firm.

Preheat oven to 325 and have a ready a parchment lined baking sheet.

Take one section of dough out of the refrigerator. Take the slab of firm dough out of the bag and set it on top of the bag or a piece of parchment paper. Using a 2-inch round cutter, cut into about 20 circles. Arrange the circles on the baking sheet and bake at 325 for about 15 minutes. While the cookies bake, repeat with the second section of dough.

Allow the cookies to cool while you make the ganache.

In a small saucepan, heat the cream and the chocolate, stirring until mixture is melted and smooth. Remove from heat and stir in the sugar. Let mixture cool and thicken slightly, then transfer to a pastry bag fitted with a narrow round tip. Alternatively, if you’ve reserved one of the freezer bags used for the dough and it is still clean, you can use that and snip off the tip.

Turn half of the cookies upside down and add a dot of ganache. If the ganache is runny, put the cookies ganache side up on a plate in the freezer to set. If you’ve cooled the ganache you shouldn’t have to do this right away. Once you’ve put ganache on each cookie, cap it with a second cookie and freeze until firm. When firm, take the cookies out of the freezer and make scribbles on top of each with the remaining ganache.