Preheat the oven to 325F and lightly grease a 9-inch ceramic or glass tart pan.
In a medium bowl, whisk together the almond flour, cocoa powder, sweetener, and salt. Stir in the melted butter until the mixture resembles coarse crumbs.
Press firmly and evenly into the bottom and up the sides of the pan (if your pan is deep dish, take the crust to about 1 inch from the top). Crimp the edges decoratively as desired.
Bake 12 minutes, then remove and let cool completely.
In a heatproof bowl set over a pan of barely simmering water, melt the chocolate and butter together, stirring until smooth. Set aside to cool.
In the bowl of a stand mixer or another large heatproof bowl, combine the egg whites, 1/4 cup of the powdered Swerve, and the BochaSweet. Set over the same pan of simmering water and whisk continuously until the whites reach 160F on an instant read thermometer.
Transfer the bowl to a stand mixer (or use a hand mixer). Add the cream of tartar and the salt and beat on high until stiff peaks form.
In another large bowl, beat the whipping cream with the remaining 1/4 cup of powdered Swerve, the vanilla, and the espresso powder, if using.
Fold about 1/3 of the egg whites into the chocolate to lighten it, then fold the chocolate mixture carefully back into the egg whites. Genly fold in the whipped cream until no streaks remain.
Spread the mixture into the cooled crust, mounding toward the center. Refrigerate for at least 4 hours or up to overnight. If overnight, press plastic wrap gently over the surface of the pie.
In a large bowl, combine the cream and powdered Swerve. Beat until stiff peaks form. Spread over the top of the pie before serving.
Yes, I really do recommend dividing this pie into 12 servings. It's very rich and the small slices are enough to satisfy.