Preheat the oven to 350°F.
In a medium bowl, combine the flour, powdered sugar, and salt. Add the softened butter and mix until crumbly.
Stir in the egg yolk and ice water until the dough comes together.
Divide the dough into 12 equal pieces and press each piece into the bottom and up the sides of a mini muffin tin. Prick the bottoms with a fork.
Bake the crusts for 15 minutes or until lightly golden. Remove from the oven and let cool slightly.
In another bowl, whisk together the granulated sugar, eggs, lemon juice, lemon zest, and heavy cream until smooth.
Pour the filling into the cooled tart shells, filling each about 3/4 full.
Bake for an additional 15-18 minutes, or until the filling is set. Let cool completely before removing from the tin.
Serve chilled or at room temperature.