Add the flour, sweetener, salt and butter to a food processor. (See the tips section for how to make this crust by hand).
Pulse until a course mixture is formed and there aren't any butter chunks much larger than a pea.
Pour this mixture into a large bowl and sprinkle on 5 tbsp ice cold water.
Use a spatula to press the mixture until it starts to come together (it's normal for it to be dry). Try not to over-work the dough.
Use your hands to form the crumbly dough into a rough ball. Wrap it in saran wrap and place it in the fridge to chill for at least 1 hour.
After an hour, remove the keto pie dough from the fridge, un-wrap it and place it on a large lightly floured piece of parchment paper (use more keto flour or vital wheat gluten for flouring). Let it sit for 5 min.
After 5min, sprinkle the top of the dough with keto flour or vital wheat gluten and top with another large piece of parchment paper use a rolling pin to hammer out the dough until it's more of a thick round disc.
Roll the dough out between the two pieces of parchment paper to form a large circle. Invert your pie pan on top of the dough and use it to measure. You'll want your dough rolled out thin enough that it's about 1-inch wider than the pie pan.
Once you've rolled your dough out into a large enough circle, carefully peel the parchment paper away on both sides.
Drape your dough over the pie pan and gently press it down to fit alone the bottom and up the sides of the pan. Fold the excess dough inward and pinch it into the rest of the dough, making sure the edge of your pie crust doesn't go beyond the edge of the pan.
Optionally you can also crimp the edges of your pie crust using your fingers (see video).
Use a fork to poke plenty of holes in the base of the crust and then cover carefully with plastic wrap and place back in the fridge for ~30min to an hour. Meanwhile, pre-heat your oven to 400*F. Place a large baking sheet inside to pre-heat as well.
Right before baking, place a piece of parchment paper in the center of your pie crust (it should be large enough that it covers the sides as well and the edges stick out above the pan). Use dry rice or beans to weigh the parchment paper down to prevent the crust from rising in the oven.
Bake the crust in the pre-heated baking sheet for ~15min, then remove the parchment containing the rice or beans, cover the edges of your crust loosely with tinfoil and place back in the oven for another 15-20min or until golden brown. *If your crust rises a bit, this is okay, it typically will deflate after coming out of the oven and cooling.
Let the crust cool completely. (I actually recommend to freeze it before using it again). before adding filling and baking again at 350*F just until filling is cooked. Feel free to add an egg wash along the edges of the pie if you wish. If you find the crust browning too quickly, cover the edges with tinfoil.