Prepare the Simple Tart Dough:
In the bowl of a food processor fitted with the blade attachment, pulse together the flour, butter, and salt until the mixture resembles cornmeal.
In a small bowl, whisk together the condensed milk and egg. While pulsing, slowly pour this into the flour until the dough just comes together.
Turn the dough out onto a lightly floured work surface and gently turn over a few times until it is smooth, the dry ingredients have been completely integrated, and the dough holds together. Take care not to overwork it.
Shape the dough into a loose circle, cover it with plastic wrap, and allow to rest in the refrigerator for at least 20 minutes.
Prepare the crust:
Preheat the oven to 350°F. Roll the dough into a rough 11- inch round. Line a 9-inch round or square tart pan with the dough and prick all over with the tines of a fork. Freeze the dough for 20 minutes. Line the dough with parchment, fill it with pie weights or dried beans, and blind bake it for 20 minutes. Remove the weights and parchment and bake the crust for 10 to 15 minutes more, until the bottom no longer looks raw and wet.
Prepare the filling:
In a small bowl, whisk together the flour, baking powder, and salt. Set aside.
Chop the dates into very small pieces. Place them in a small bowl and add the hot coffee and baking soda and stir. Set aside until cooled.
In the bowl of an electric mixer fitted with the paddle attachment, beat the butter and brown sugar until light and fluffy. Add the eggs one at a time and then the lemon zest and vanilla; beat until blended. Gradually add the flour mixture and mix until just combined.
Remove the mixing bowl from the machine and fold in the date mixture by hand, using a rubber spatula. Pour the filling into the prepared shell. Bake until the pudding is set, 30 to 35 minutes.
Prepare the sauce:
Combine the butter, cream, brown sugar, and salt in a heavy-bottomed saucepan over medium-low heat. Stir constantly until the sugar has completely melted, then raise the heat to medium and simmer gently until the sauce thickens, about 10 minutes.
Finish the tart by spreading 1 cup of the sauce over the top of the tart. Serve it immediately, drizzling a little more toffee sauce over each piece.
Adapted from Pie It Forward