Cream your butter and sugar together. If using a stand mixer, you can top the butter in at any temperature and the mixer will soften it. If mixing by hand, allow your butter to soften slightly at room temperature, or blitz it in the microwave for 5 - 10 seconds.
Combine your potato starch and water; mix until the flour completely dissolves. Add your potato starch egg into the creamed butter and sugar.
Add almond flour, all-purpose flour, and salt. Don’t overmix!
Now, shape the dough loosely into a ball. Transfer it onto a large silicone baking sheet or floured surface. Place a second silicone baking sheet over the dough or dust with all-purpose flour to prevent sticking.
Set your rolling pin set to a maximum ⅙” thickness and roll the dough flat. Allow the dough to rest in the fridge for 30-60 minutes.
Preheat your oven to 375 degrees F.
Remove the pâte sucrée dough from the fridge after it has chilled. If you used a second baking mat to smooth the dough, peel it away.
Flip the sheet over so the dough is on the underside of the baking sheet and directly resting on top of the tart pan. Peel the silicone baking mat away from the dough. Your dough will be draped across the tart tin.
Gently prod the dough to fit the tart pan. Patch and smooth small cracks with extra dough pinched off the sides.
Use a fork to puncture venting holes along the base of the shaped shortcrust dough.
Bake the pâte sucrée for 12 - 18 minutes, or until lightly browned. Remove the parbaked shortcrust and allow to slightly cool before adding the frangipane filling.