Preheat the oven to 400°F.
For the Almond Tart Shell: combine all tart ingredients in a stand mixer and mix with the paddle attachment until the it resembles small peas or corn meal. Dump the dough into an 8-in round or 13 X 3.5-in rectangular tart shell pan, pressing dough into bottom and up sides with your fingers to form a nice crust. Bake for about 35 minutes or until the shell turns a light golden brown. Set aside to cool before filling.
Meanwhile, in a large bowl, gently toss peach slices with flour, sugar, and salt.
In another bowl, cream together cream cheese, sugar, egg and orange zest. Spread, very carefully, in a thin layer over the tart shell.
Arrange the fruit and its mixture either in rows on top of the pastry or, for a more rustic look, pile it on top and then spread it out with your hands until even.
Bake, loosely tented with foil, until fruit has softened for about 20 minutes depending on your oven so check it regularly from 10 minutes on. Remove from oven.
Brush the tart border and the fruit with the warm marmalade and turn the oven to broil and let it cook for another minute – just long enough to get a nice caramelized glaze but not long enough to burn.
Remove from oven and sprinkle with sliced almonds.
Let cool to room temperature. Cut into pieces and enjoy!