In a large mixing bowl, combine the flour, salt, and sugar. Add the chilled butter cubes and use your fingertips or a pastry cutter to blend until the mixture resembles coarse crumbs.

Gradually add ice water, one tablespoon at a time, mixing until the dough comes together. Divide the dough in half, shape into discs, and wrap in plastic wrap. Refrigerate for at least 30 minutes.

Preheat the oven to 425°F (220°C).

In a saucepan, combine the huckleberries, sugar, cornstarch, lemon juice, and cinnamon. Cook over medium heat until the mixture starts to thicken and bubble, about 5-7 minutes. Remove from heat and let cool slightly.

On a lightly floured surface, roll out one dough disc into a round shape that fits your pie dish. Place the rolled dough into the pie dish, pressing it down gently.

Pour the huckleberry filling into the crust, spreading evenly. Dot with small pieces of butter.

Roll out the second dough disc and place it over the filling. Seal the edges by crimping them together, and make a few slits in the top crust to allow steam to escape.

Bake in the preheated oven for 40-45 minutes or until the crust is golden brown. Check the pie during the last 15 minutes to prevent over-browning. If necessary, cover the edges with foil.

Once baked, remove the pie from the oven and allow it to cool on a wire rack before serving.