Make the cookies: in a medium bowl, whisk together the flour, baking soda, and salt. Set aside.
In a larger bowl, add the butter and sugars. Mix (either by hand or using an electric mixer) until smooth.
Add the egg, vanilla extract, and water to the butter mixture and mix until thoroughly incorporated.
Add the chocolate chips and dry ingredients, then use a spatula to gently fold them together, being careful not to overmix.
Using a small ice cream scoop or spoon, measure out 6 tablespoon-sized balls of dough and space them 2-3 inches (5-7 cm) apart on a prepared baking sheet.
Bake the cookies for 18 minutes. They should be thin with crispy edges when finished.
Remove the cookies from the oven and allow them to cool for 5 minutes on the baking sheet before transferring them to a wired cooling rack. Bake off the second half of the dough and allow all the cookies to reach room temperature before proceeding.
Once thoroughly cooled, place the baked cookies back in the oven, directly on the oven rack, and toast them at 325˚F (160˚C) for 7 minutes. This will completely dry out the cookies leaving them very crispy and brittle.
Carefully transfer all the toasted cookies to a parchment-lined baking sheet. Using the back of a heavy spoon or measuring cup, firmly smack the top of the cookies. Set the baking sheet of shattered cookies aside.
Make the bark: slowly melt 1 pound (455 g) of the baking chocolate either in a double boiler or in a glass bowl over just-simmering water. Allow the chocolate to melt undisturbed until about two-thirds of it has melted, then stir until it is completely smooth with no visible chunks.
Remove the chocolate from the heat and allow it to cool for 10 minutes before adding in the remaining chocolate. The residual heat will melt the solid chocolate. Mix until smooth.
Arrange the shattered cookie pieces in a layer on the baking sheet. Pour the melted chocolate over the pieces and use a spatula to quickly and evenly spread the chocolate across the tops of the cookie pieces.
Sprinkle with salt and any other desired toppings. Transfer the baking sheet to the refrigerator for at least 30 minutes for the chocolate to set.
Once the bark is set, remove the baking sheet from the refrigerator and cover the bark with parchment paper. Use something heavy (like a meat tenderizer) to break the bark into snack-sized pieces.
Serve the pieces immediately or store in the refrigerator until desired.
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