Make the crust: In a large bowl, whisk the melted butter, maple syrup, and egg to combine. Add the almond flour, tapioca starch, and salt. Mix to thoroughly combine. If the dough is still sticky, add a tablespoon of tapioca starch at a time until you’re able to form it into a ball without it sticking to your hands. Press into a 10-inch tart pan. It will be thin, so take your time to get it spread out and up the sides. Place on a baking sheet (It’s easier to move in and out of the oven this way)
Make the custard: Heat the coconut milk in a medium sauce pan until steaming. In a large bowl, whisk the eggs with the maple syrup, vanilla extract, and salt. Gradually whisk in the heated coconut milk.
Pour the custard into the prepared tart shell through a fine mesh sieve (to catch any cooked egg bits).
Bake for 25-30 minutes, or until the custard is set in the center. Allow to cool for 20 minutes or so before transferring to the fridge to chill completely.
When ready to serve: slice the nectarines thinly and arrange on top
Notes
For a nut-free version, use the crust from this tart instead.