Combine blackberries, 1 tablespoon erythritol, lemon juice, and xanthan gum in a bowl using a spoon and make sure everything is coated well. Transfer to a 8-inch oven safe skillet.
In another bowl, add egg, melted butter, remaining erythritol, stevia and vanilla, whisking until combined. Add the almond flour and whisk until a thick dough forms, changing over to a spatula when necessary.
Spread the dough over the berries and bake for 20-25 minutes, until the top is golden brown and the berries are bubbling.
Let set for 5 minutes before serving. If desired, serve alongside your favorite low carb ice cream (we love Rebel and So Delicious!).
Best stored in an air tight container int he fridge up to 5 days.