Make the Crust:  Preheat the oven to 350 degrees.  Spread almonds out on a rimmed baking sheet.  Bake until toasted and fragrant, about 8 minutes.  Set aside to cool to room temperature.

Add toasted nuts to the work bowl of a food processor.  Process until finely ground.  Add flour, sugar and salt and pulse a few times to combine.

Scatter butter over the top of the flour mixture and pulse 8-10 times or until the mixture is the texture of wet sand.

Sprinkle water and vanilla extract over the top and pulse until dough just begins to clump together.

Transfer dough to a 9-inch round fluted tart pan with a removable bottom.

Press dough into an even layer over the bottom and up the sides of the tart pan creating a crust.  Flour the bottom of a metal measuring cup and press it over the bottom and sides of the crust to help even everything out.  Freeze until firm, about 20 minutes.

Meanwhile, make the Filling:  Whisk all the filling ingredients except the flour together in a medium bowl.  Sift flour over the top and whisk thoroughly to combine.  Pour filling into the frozen tart shell and place on a rimmed baking sheet.  Bake the tart until it is set and golden brown, about 30-35 minutes.  Serve slightly warm or at room temperature.