1. In a bowl, combine flour and sugar and cut in butter until butter resembles small peas. Make a hole in center of flour mixture and add egg and vanilla and mix until just combined.
2. On a lightly floured surface, turn dough out and knead, adding water if needed. Return dough to bowl, cover in plastic wrap, and refrigerate for 1 hour.
3. Remove from refrigerator and on a lightly floured surface, roll out dough into a circle then press down and with fingers to form a larger circle that will fit into tarte pan.
4. Line an 8-in (20-cm) tarte pan with parchment paper. Carefully place dough in pan and form edges with fingers.
1. Distribute chocolate and berries evenly on bottom of shell, carefully cover with plastic wrap, and refrigerate.
2. In a stainless steel bowl or mixer, whip cream, then cover in plastic wrap and set aside in refrigerator.
3. In a different or cleaned bowl of mixer, combine butter and sugar and whip on medium-high speed until well combined.
4. Add egg and whip until light and fluffy and color changes from yellow to white. Stop mixer and add flour. On low speed, mix until just combined. Do not overmix.
5. With a wooden spoon or rubber spatula, fold in pre-whipped cream.
Assembly and Cooking
1. Preheat oven to 350°F (180°C).
2. Remove tarte pan from refrigerator, carefully uncover, and pour filling evenly over berries and chocolate.
3. Place tarte pan on a baking sheet and bake 45 minutes or until golden brown. Remove from oven and let cool for 2 hours before serving.