In a medium bowl, mix together the flours, xanthan gum, sea salt, and sugar until combined. Add the melted coconut oil and mix until well combined. Add the cold water and work the mixture until dough forms.
Press the dough into a 9-inch tart pan using your fingers and the palm of your hand. Try to make the crust even throughout. If it helps, use the back of a large spoon to smooth out any lumps. Place the tart crust in the fridge for at least 10 minutes.
Line the crust with parchment paper. (Crunch up the paper first so that you can easily shape it into the crust.) Fill with pie weights or uncooked rice or beans. Bake at 350° for 15–20 minutes until lightly browned.
Remove the pie weights and parchment and allow crust to cool.
In a medium saucepan, heat the coconut cream over medium heat until it starts to bubble but does not boil. Remove from heat and stir in chocolate. Whisk until chocolate has melted and is fully incorporated with cream. It will turn into a homogeneous, smooth ganache.
Pour warm ganache into cooled crust. Refrigerate the tart for at least five hours or overnight. Serve garnished with sea salt, cacao nibs, and/or berries.
Read more: This recipe originally appeared in "Sweet Surprise" by Chef Johnny Vee.