For the pâte sucrée:
1. Put the butter, confectioner's sugar, almond flour, orange zest and vanilla extract in the bowl of an electric mixer fitted with the paddle attachment. Mix on medium-low speed just until the ingredients are combined, about 20 seconds. Add the flour and mix 20 seconds, just until the dough is crumbly. Add the egg and 1 tablespoon of water and mix only until the mixture comes together to form a moist, soft dough. You don't want to overwork the dough. (Add remaining tablespoon if needed.) Turn the dough out onto a work surface, flatten the dough into a disk and wrap in plastic wrap. Chill for at least 1 hour. (The dough can be made to this point, wrapped airtight and kept refrigerated for two days or frozen for up to a month.)
2. Place a buttered 8 1/2-by-1 1/2-inch fluted removable bottom tart pan on a parchment-lined baking sheet. Dust a work surface lightly with flour and roll the dough into a round that is about 1/8-inch thick. Fit the dough into the bottom and up the sides of the pan, taking care not to stretch the dough. Remove the excess dough from the sides and use the tines of a fork to prick the dough all over. Refrigerate for at least 30 minutes.
3. Preheat the oven to 350 degrees F. Line the pastry shell with parchment paper and fill with dried beans. Bake the crust 10-12 minutes, remove the paper and beans and return to the oven for 3-5 minutes more. You do not want to brown the dough too much at this point since it will be baked again later — you just want to cook the dough enough to prevent it from becoming soggy once filled. Cool on a rack to room temperature.
For the almond cream:
Put the butter, sugar and almond flour in the bowl of an electric mixer fitted with the paddle attachment and beat on medium-low speed until the ingredients are well blended. Add the egg and flour and beat on medium speed until homogeneous. Cover and refrigerate until needed.
For the peaches:
Combine the water, sugar and vanilla bean pod and seeds and bring to a boil. Add the peach halves, bring back to a boil and simmer until tender when pierced with the tip of a paring knife, approximately 5-10 minutes depending upon ripeness. Remove from heat and set aside to cool.
For the thyme streusel:
Put the two flours along with the sugar, thyme and salt in a food processor and pulse a couple of times to mix. Add the cubed butter and pulse just until the streusel forms small, moist curds. Pour into a bowl, cover and refrigerate until needed.
To bake the tart:
Preheat the oven to 350 degrees F. Fill the partially baked crust (still on the parchment lined tray) halfway with almond cream. Drain the peaches, discarding the vanilla bean pod, and pat them dry with paper towels. Arrange them, domed side up, on top of the almond cream and then sprinkle with the streusel. Bake until the top is golden brown, approximately 35-40 minutes. Cool on a rack to room temperature before unmolding.
The tart can be served either at room temperature or slightly warm and is perfect accompanied by a scoop of vanilla ice cream.