Make the crust by pulsing the gluten free flour, cold cubed butter, sugar, salt, and xanthan gum in a food processor until the mixture resembles coarse crumbs. Drizzle in the ice water one tablespoon at a time, pulsing until the dough just comes together. Flatten into a disc, wrap in plastic, and refrigerate for 30 minutes.
Roll the dough out between two sheets of parchment paper to a 12-inch round. Carefully transfer to a 9-inch pie plate, pressing into the edges. Trim and crimp the edges as desired. Prick the bottom with a fork and refrigerate for 15 minutes. Preheat your oven to 350 F.
Line the chilled crust with parchment paper and fill with pie weights or dried beans. Blind bake for 15 minutes, then remove the weights and parchment and bake for another 5 to 7 minutes until the bottom looks dry and lightly golden. Set aside.
Whisk together the honey, melted butter, eggs, sugar, cornstarch, apple cider vinegar, vanilla, and sea salt in a large bowl until smooth and well combined.
Stir in the heavy cream until the filling is silky. Pour the filling into the warm par-baked crust.
Bake for 40 to 50 minutes until the edges are set but the center still has a gentle wobble, similar to a custard pie. If the crust edges brown too quickly, cover them with foil.
Let the pie cool completely at room temperature, then refrigerate for at least 2 hours until fully set. Before serving, sprinkle the top generously with flaky sea salt.