Preheat the oven to 350°F. To make the crust, combine all the crust ingredients and use your hand to mix the dough until a ball forms. (We halved the recipe so we ended up using 1/2 a beaten egg for the crust)
Press the crust mixture into as many tartlet pans as you can. We were able to press the dough into 2 5 inch, removable bottom pans. Bake the crusts in a 350°F oven for about 12-15 minutes, checking often.
While the crusts are baking, zest 1 lemon into a small bowl. Juice the same lemon plus 1 more into the same bowl and set aside.
Separate 3 egg yolks and whisk them with 1/4 cup of powdered erythritol and stevia drops until they’re a bit paler in color. Set those over a double boiler and whisk for about 10 minutes until they begin to thicken.
Add in lemon juice and zest and whisk the egg yolks until warm again. Add a pinch of xanthan gum to help thicken your lemon curd.
Add in a bit of butter at a time, whisking until each piece is completely combined. Refrigerate until ready to use.
To make the meringue, whip 2 egg whites with an electric hand mixer on low speed until frothy (about 5 minutes).
Add cream of tartar and whip to combine. Then add 1 tablespoon of erythritol at a time while whipping on medium speed. Now whip on high speed until you get stiff peaks in the egg whites, about 5 more minutes.
To arrange the lemon meringue tartlets, divide the lemon curd evenly on top of the crusts and then add a generous dollop of meringue. Bake in a 325°F oven for about 12 minutes or until the tops are golden.