Preheat the oven to 375-degrees.
For the pastry crust:
Cut the butter into cubes and chill in the freezer for about 30 minutes. Combine the flour, toasted almonds, kosher salt and 1 tablespoon of the sugar into the bowl of a food processor. Process the flour mixture for about 15 to 20 seconds or until the almonds are finely ground.
Scatter the cold butter cubes on top of the flour mixture and pulse about 10 times, just until the butter is the size of peas.
Pour the cold water over the top of the flour and butter then process for about 10-15 seconds or just until the pastry starts to come together. It will still be crumbly but don’t over process or your pastry will be tough.
Turn the pastry dough out onto a lightly floured surface and lightly dust your hands with flour. Gently pull the dough together and divide it in half for two small tarts. Gently press each half into a disc. Roll the dough into rounds, each about 10” to 12” in diameter and about 1/8” thick. Turn the dough occasionally and lightly dust the surface as needed to keep the dough from sticking. You can also make one large tart, rolling the dough out to about 15” to 16” in diameter.
Wrap the dough around the rolling pin and gently unroll onto a parchment lined baking sheet.
For the peach filling:
In a small bowl whisk the cornstarch and sugar together.
Toss the sliced peaches into a large mixing bowl. Stir the cornstarch and sugar into the peaches along with the nutmeg, almond extract and lemon juice.
Using a slotted spoon or your hands scoop up the sliced peaches and pile them into the center of the pastry dough. There will be a fair amount of juice after you mix the peaches with the sugar – you want to limit the amount of liquid placed on top of the pastry dough. Leave about 2” to 3” around the edge.
Turn the edge of the pastry dough up over the peaches, folding as you go.
Whisk the egg and 1 tablespoon milk together. Using a pastry brush, lightly brush the egg wash over the pastry dough. Sprinkle the top of the dough with the remaining 1 teaspoon of sugar.
Bake the tarts in a 375-degree for 45 minutes or until the crust is golden brown.
Warm the preserves in a small pan over medium heat until they are very loose. You can also warm them in the microwave for about 30 seconds. Brush the exposed fruit with the warmed preserves.
Let the tart cool slightly before slicing to allow the juices to set.