Whisk together egg and heavy cream.
Place flour, sugar and salt in mixer and mix on low.
Add butter and pulse or mix on low until you arrive at a cornmeal consistency.
While mixer is on low add egg mixture and mix until at least 2/3 of the ingredients form a dough.
Tip out dough onto a floured surface and mold dough into a circle shape.
Cover dough with plastic wrap and place in fridge for 30 mins.
Remove from fridge and roll out to at least an inch larger than the tart pan on all sides.
Fold dough in half, then in half again, then carefully place it in the middle of the tart pan and unfold dough to cover tart pan
Carefully push dough into the corners and edges and trim excess dough by rolling pin on top of the tart pan.
Prick base with a fork a few times then place in the fridge for 30 mins.
After 30 minutes remove tart pan from the fridge.
Cut a piece of parchment paper the size of the tart pan and place on top of the dough, then carefully tip pie weights on top.
Place tart pan in a preheated oven at 350 and cook until golden.
Once pastry is golden remove from oven and set aside.