Chocolate Tart Dough

Directions

1. 1
   Put the butter in the bowl of a standing mixer fitted with the paddle along with the sugar and a pinch of salt.
2. 2
   Beat until pale.
3. 3
   In a separate bowl, whisk the egg and egg white together.
4. 4
   Add gradually to the butter, scraping the bowl often and beating until smooth.
5. 5
   Whisk the flour, cocoa powder, and baking powder together.
6. 6
   Add to the wet ingredients and mix on low speed only until blended.
7. 7
   Dump the dough onto a lightly floured work surface and divide in half.
8. 8
   Shape each half into a small brick, wrap in plastic, and refrigerate for at least 1 hour before rolling.
9. 9
   The dough will keep for several days in the refrigerator and for 2 months in the freezer.
10. 10
    Defrost before rolling.
11. 11
    Add 1/2 teaspoon (0.5g) ground allspice and 1/8 teaspoon (0.2g) ground cinnamon to the bowl when you are beating the butter and sugar.