I first made a version of these treats at my friend Douglas' cafe The Mason Jar in Cheney, Washington. I was visiting and he was hosting a book club at the cafe. And you know, friends help friends bake. I love that you can prep everything in advance and then assemble just in time to wow guests with tiny treats it looks like you spent 15 hours on. (You didn't).
1 cup all-purpose flour
1/3 cup Dutch cocoa powder
1/4 teaspoon baking soda
1/2 cup unsalted butter, at room temperature
1/2 to 2/3 cup granulated sugar
1/4 teaspoon fine sea salt
1 large egg yolk
1/2 teaspoon vanilla extract
3 1/2 ounces bittersweet chocolate, grated
1 cup whipping cream
6 oz good quality dark chocolate
1 cup sea salted caramels, chopped
Sift together the flour, cocoa and baking soda together and set aside.
Cream butter, sugar and salt together in a large bowl with an electric mixer until light and fluffy. Add egg yolk and vanilla, beating until combined, then scraping down sides. Add dry ingredients and grated chocolate together and mix until just combined.
Scrape dough onto a piece of plastic wrap, wrap it up and chill it in the fridge about 30 minutes.
Heat oven to 350 F. On a floured surface, roll dough gently — it will still be on the crumbly side, so only attempt to flatten it slightly with each roll — until it is 1/8-inch thick. Cut into desired shapes and space them an inch apart on a parchment-lined baking sheet. Bake for 8 to 10 minutes. Leave cookies on baking sheets out of the oven for a couple minutes before gently, carefully transferring them to cooling racks, as they’ll be fragile until they cool.
Melt chocolate in a double boiler. When melted remove from heat and allow to cool slightly.
Beat whipping cream until stiff. Mix a small amount into the melted chocolate to lighten and then pour chocolate into remaining whipping cream. Fold together, being careful not to deflate.
Scoop mousse into piping bag with star tip. Decoratively pipe a small pile onto each cookie. Sprinkle with salted caramel pieces.