Preheat the oven to 170°C/338oF and place a mold with water on the very bottom. It will help to make steam inside the oven and prevent your dessert from overdrying. Cover a baking form with a baking paper and lightly grease it with butter.
Now let’s make the crust. Mix the coconut flour, coconut oil, cream, erythritol, and xanthan gum into a smooth dough. Place it into a mold and flatten. Bake for about 15-20 minutes, until nice golden color.
The next step is a lemon layer. Mix all the ingredients with a blender till smooth. Pour the cream over the crust and return the form to the oven for another 15-20 minutes. Check the lemon cream for readiness: if you wiggle the form, the center of the cream should be almost still.
Put the tart out of the oven and let it cool in the form. Then remove it to the fridge for at least 2-3 hours until completely solidified. Slice the cooled tart into 10 pieces. Serve with coconut flakes, lemon zest, or rosemary leaves, if desired.