Preheat your oven to 200 degrees. Line a baking sheet with parchment paper and set aside.
In a stand mixer beat the egg whites and cream of tartar at high speed until soft peaks form. Sprinkle Swerve and vanilla in and then beat until stiff peaks form.
Divide the meringue into 4 piles on the baking sheet, then, with the back of a large spoon, shape the mounds into a 4-inch (ish) “nest” with a bowl shape in the middle.
Bake just until the meringues begin to color ( about 2 hours) and then turn off the oven. Let them sit in the oven for another hour or overnight. Cool completely on a wire rack and then store in an airtight container until ready to use. They should last several days.
For the filling:
In a stand mixer with a whisk attachment, add the mascarpone, monk fruit sweetener, vanilla and orange zest and beat at high speed until the mascarpone is light and fluffy. Add the cream and beat until stiff peaks form (this may take 5-8 minutes or so).
Fill each meringue shell with mascarpone cream filling and top with fresh berries. Serve immediately!