For the pate sablee tart crust: Preheat the oven to 350 degrees F.
Cream together the butter, sugar and salt in a stand mixer fitted with the paddle attachment. Mix in the eggs, one at a time, scraping the bowl after each addition. Add the flour and mix on low speed until just incorporated.
On a flour-dusted work surface, roll out the dough to a 1/4-inch thickness, and then cut into 6-inch circles. Line eight 4-inch tart pans with the pastry and refrigerate for 30 minutes.
Prick the bottom of the chilled tart shells with a fork. Bake until the shells are an even golden brown, 15 to 20 minutes. Cool completely before filling.
For the mascarpone cream cheese filling: Cream together the mascarpone and cream cheese in a stand mixer fitted with the whisk attachment.
Add the cream, confectioners' sugar and salt and continue beating until light and fluffy, about 5 minutes.
Once the filling is smooth, add the lemon zest and candied ginger and mix to combine. Transfer the filling to a pastry bag fitted with a large round tip.
For the sugar-roasted summer squash: Once the tart shells are out of the oven, raise the oven temperature to 425 degrees F.
With a mandolin, thinly slice the squash into disks.
Combine the sugar and five-spice powder in a large bowl. Add the sliced squash and toss to coat.
Place the sugar-coated squash on parchment-lined baking sheets, leaving some space between each slice.
Roast until the squash is beginning to brown at the edges and the sugar is starting to caramelize, 15 to 20 minutes. Remove from the oven and let cool to room temperature.
To assemble: Fill the cooled tart shells with the filling. Decoratively arrange the cooled squash slices on top. If desired, use a kitchen torch to caramelize the edges of the squash.
This recipe was created by a contestant during a cooking competition. It has not been tested for home use.