In a stand mixer, toss the butter and sugar together. Beat on medium until smooth and there are no lumps. Add in the egg yolks, mixing in each yolk thoroughly.
In a separate bowl, whisk the flour and sprinkle the salt over the flour. Slowly pour the flour into the butter mixture while the mixer is on low. Once all the flour is added, beat until the flour is thoroughly mixed in.
If the dough is not coming together, add in the tablespoon of water and mix well until a dough forms.
Divide the dough into two and flatten into rectangles or a circle if you are using a circular tart pan (you will only use one of these discs in this recipe. You can keep the other disc in the refrigerator for two weeks, or in the freezer for up to a month. Chill for one hour. Once the dough has chilled, roll out one of the discs of dough until it is large enough to fit your tart pan. Place in the tart and trim the edges as needed. Chill again for another 30 minutes.
Preheat the oven to 375 degrees F. Prick the tart bottom and sides with a fork. Fill with pie weights (or line with parchment paper and place dry beans or rice to weigh the tart down). Bake for 10 – 15 minutes, or until a light golden brown. Remove the weights and set aside to cool.
For the Raspberry Compote
In a small saucepan, add the raspberries, sugar, salt, and ginger. Heat on medium for about 5 minutes and mash the raspberries occasionally. Set aside to cool.
For the Mascarpone Filling
Mix together the mascarpone, whipping cream, sugar, lemon zest, and vanilla together. Beat until stiff peaks form.
To Assemble
Fill the tart with the mascarpone filling. Brush the mascarpone with a thin layer of the compote. Top with the blueberries. Chill for about 30 minutes before serving. Can keep in the refrigerator in an air tight container for up to 3 – 5 days.