To prepare the pastry:

Pulse the cold butter and shortening into the flour, sugar, and salt using a food processor until the shortening or butter is reduced to pea-sized pieces

Sprinkle the water over the surface and toss with a fork until the water is incorporated into the dough. Do not overwork the dough; handle it only enough so that the dough stays together

Form the dough into two rounds about an inch thick

Wrap in plastic wrap and rest in the fridge for about half an hour.

Roll out on a lightly floured surface. Cut into rounds with a 4-inch cutter. Fit into muffin cups. Chill in the fridge or freezer while you prepare the filling. Cold pastry heading into a hot oven will always be flakier

Filling:

Preheat oven to 425°F

In a medium bowl, mix brown sugar and salt. Add the butter and beat by hand until smooth. Add the vanilla and egg and mix until combined. Do not use an electric mixer.

Divide the filling into the tart shells until about half full. Place the muffin tin on a baking sheet. Bake 12-15 minutes for a runnier tart or 17-19 for a firmer tart*

Remove from oven and run a knife around the edges of each tart to loosen. Cool completely in the tin. To remove, run a knife around and under each tart and pop out. Serve warm with fresh whipped cream