Slowly add the water with the machine running just until the dough forms a ball.
Chill for at least 2 hours.
Roll into tartlet molds, chill for 30 minutes, dock, and then blind bake at 400 degrees for around 20 minutes, or until crust is golden and flaky (see notes).
Notes
You need to work very carefully with the dough here. Since the tartlets are small, you want to roll the dough as thin as possible. Paper thin, if you can. If there is a lot of dough in each tartlet, the filling won’t stand out.While working with the dough, you always want it to be cold. Pâte Brisée can become elastic once it gets too soft or overworked. Break up the dough into separate pieces and work with a small amount at a time while the rest is being chilled. If you keep balling it up and trying to roll it out again, it will shrink. This doesn’t matter so much with something like a galette, but with small tarts you want the walls to extend all the way up.After you roll the dough into the tartlet molds, chill for at least 30 minutes. Then poke numerous tiny holes the dough with a small point such as a fork, bamboo skewer or push pin. This is known as docking and it will prevent air bubbles from forming and causing the dough to rise.After you dock the dough, place parchment paper in the middle of each tart, then topping with uncooked beans. This is additional protection against the dough rising.