In a large bowl, whisk together the flour, cocoa powder, brown sugar, and granulated sugar.

Add the cold butter slices and toss to coat in the flour mixture.

Use a pastry cutter or fork to cut the butter into the flour until it resembles small pea-sized crumbs.

Gradually add the cold water, 2 tablespoons at a time, mixing until a dough forms that pulls away from the sides of the bowl.

Shape the dough into a flat disk, wrap tightly in plastic wrap, and refrigerate for 30 minutes.

In a large bowl, gently mix together the cherries, brown sugar, cornstarch, bourbon (if using), vanilla, and lemon zest. Set aside.

Preheat your oven to 400°F (205°C) and line a baking sheet with parchment paper or a silicone mat.

Remove the chilled dough from the refrigerator and place it between two sheets of parchment paper. Roll it into a 12-inch circle.

Trim the edges for a cleaner finish, using a large plate or bowl as a guide if desired.

Transfer the dough to the prepared baking sheet.

Spoon the cherry mixture onto the center of the dough, leaving a 2-inch border around the edges. Discard any excess liquid.

Fold the edges of the dough over the cherries, creating pleats as you go.

Bake the galette for 35-40 minutes, until the crust is firm and the cherries are bubbly.

Remove from the oven and let it cool for 10 minutes.

In a medium bowl, beat the heavy whipping cream, sugar, and bourbon (if using) with an electric mixer on medium-high speed until stiff peaks form.

Spoon the whipped cream over the cooled galette and dust with cocoa powder, if desired.

Slice and enjoy this decadent dessert!