01 -
In a medium bowl, stir together the salt and flour. Toss the chilled butter cubes (about 1/2-1 cm pieces) in the flour, making sure not to overmix.
02 -
Pour in most of the cold water and use a blunt knife to mix into a dough. If it's still crumbly, add a bit more water, but keep it firm and not sticky.
03 -
Sprinkle your countertop with flour, then stretch the dough into a long rectangle. Fold the top section over the middle, then overlap the bottom section. Rotate the dough 90° and repeat this step two more times.
04 -
Wrap your dough tightly in plastic wrap and put it in the fridge for half an hour.
05 -
Set your oven to 200°C (400°F). Line a baking tray with parchment paper while it preheats.
06 -
Use a mandoline to slice the potatoes into thin rounds (1 mm thick). Toss them into boiling salted water for 30 seconds, drain, cool in cold water, and set them aside.
07 -
Take the chilled dough and roll it into a large rectangle (15 cm by 48 cm). Trim the edges to neaten, then slice into six even pieces.
08 -
Score a border around each pastry rectangle about 3/4 cm from the edge. Poke a few holes in the center with a fork and arrange them on the lined baking tray.
09 -
Cut the brie into thin pieces and arrange them inside the scored border on each rectangle. Layer the potato slices over the cheese in a slightly overlapping pattern. Brush olive oil over the potatoes and a beaten egg around the edges.
10 -
Sprinkle some parmesan over the assembled tarts and bake for 20-25 minutes, or until they look golden and crisp. Top them with rosemary and a tiny pinch of sea salt just before serving.