In a medium bowl, beat the butter until it is light and fluffy. Add the monk fruit, salt, and egg yolk and beat again until light and fluffy. Add in the almond powder, cocoa powder, and baking powder and beat until the batter comes together (It should have the consistency of play dough and be very smooth).

Press into a ball and then roll between 2 sheets of parchment paper. Cut into strips and transfer to 6, 3-inch tart rings. Refrigerate for 30 minutes (you can wrap and freeze the lined tart for up to 2 months - when baking, don’t thaw the pastry, just add a couple more minutes to the baking time).

Preheat the oven to 350ºF. Line the dough in the tart rings with parchment paper and fill with pie weights (rice works well). Bake at 350ºF for 8 minutes. Remove parchment and weights and bake another 8-10 minutes, until firm - they will crisp up more when cooled. Remove from oven and cool completely and set aside (if they are not firm when cool, return them to the oven and bake for another 5 minutes). These can be made up to a 2 days ahead of time and stored at room temperature.

Line 3-4, 2 3/4-inch tart rings with acetate strips. Set lined tart rings onto a sheet of acetate in a rimmed baking sheet and set aside.

Whisk the egg yolks until smooth in a medium bowl. Set aside.

Combine the gelatin, stevia, 3/4 cup cream, cocoa butter, and salt in a medium pan and let stand for 5 minutes to allow the gelatin to rehydrate. Heat over medium heat until the gelatin dissolves and the cocoa butter melts. The mixture should steam but not boil.

Slowly stream the hot cream mixture into the egg yolks while whisking the yolks constantly to temper them (prevent the eggs from scrambling). Return the mixture to the pan and continue to cook on medium until slightly thickened, about 3 minutes or so.

Remove from heat and stir in the peppermint and green color, to taste. Transfer to a bowl and let stand at room temperature, stirring occasionally until the mixture has a slight wobble but is not yet set, about 20 minutes.

Beat the remaining 1 1/4 cups cream to stiff peaks with an electric mixer. Whisk about 1/3 of this cream into the wobbly mint cream to lighten it. Fold in the remaining whipped cream until smooth.

Divide the cream between the acetate lined tart rings and smooth the tops. Transfer to a freezer and freeze until set, about 1 hour and up to overnight.

When the cream is set, remove from tart rings and peel off the acetate. Dip a knife in hot water and wipe it dry. Cut each round in half.

Set each tart shell on its side and place a cream half inside.

Make chocolate curls by scraping a knife across the surface of the chocolate bar. Sprinkle over top of the cut surface of the cream. Finally, place a mint leaf on top and serve.