Prep the pan. Line the bottom of a 9-inch springform pan with parchment. Lightly grease the sides.
Preheat your oven to 325°F (165°C).
Mix the crust. In a bowl, combine almond flour, cocoa, sweetener, salt, vanilla, and melted butter. Stir until the texture is like damp sand and holds when pressed.
Press and par-bake. Firmly press the mixture into the pan, going slightly up the sides. Bake for 10 minutes, then set aside to cool slightly.
Make the filling base. Beat the cream cheese on medium until smooth and fluffy, about 1–2 minutes.
Scrape the bowl often to avoid lumps.
Sweeten and flavor. Add powdered sweetener, cocoa powder, salt, vanilla, and espresso powder if using. Beat until fully combined and silky.
Add cream and chocolate. Slowly beat in the heavy cream. Fold in the melted chocolate (cooled slightly so it’s warm, not hot) until the batter is uniform and glossy.
Add the eggs. Beat in the eggs one at a time on low speed, just until incorporated. Do not overmix; this keeps the cheesecake from cracking.
Set up for gentle baking. Wrap the outside of the springform pan with foil to protect from water if using a water bath.
Place the pan on a baking sheet. For best results, pour about 1 inch of hot water into a larger roasting pan and set the cheesecake pan inside (water bath), or bake without the bath but avoid high heat.
Bake. Pour the filling over the crust. Bake at 325°F for 55–70 minutes, until the edges are set and the center has a slight wobble.
If using without a water bath, start checking at 55 minutes.
Cool slowly. Turn off the oven, crack the door, and let the cheesecake rest inside for 1 hour. Then move to a rack to cool to room temperature.
Chill to set. Cover and refrigerate at least 6 hours, preferably overnight, for the creamiest texture.
Make the ganache. Heat the heavy cream until steaming. Pour over chopped chocolate and let sit 2 minutes, then whisk smooth.
Sweeten to taste if desired. Let cool to a pourable but not hot consistency.
Finish and serve. Pour the ganache over the chilled cheesecake, letting it gently flow to the edges. Chill 20–30 minutes to set.
Slice with a hot, clean knife. Garnish with sea salt or sugar-free shavings.