For almond paste, add almond meal, sugar, egg white, almond extract and salt to a bowl, mix well until combined. Cover and refrigerate until ready to use. Almond paste can be prepared well in advance and store in the refrigerator for up to 10 days.
For the crust, place flour, sugar and salt in the food processor fitted with the dough blade and pulse a few times to mix.
Cube the butter and add to the flour mixture. Make sure butter is cold. Pulse several times until butter is about pea size and mixture resembles coarse crumbs.
Add cold water, 1 tablespoon at a time, and pulse until the dough starts to pull together. Be mindful not to overmix, you still want chunks of butter in the dough to create a flaky crust.
Turn the dough out on a lightly floured board and shape into a disk. Wrap in plastic and rest in the refrigerator for an hour.
Roll dough out into a circle about 1/4” thick and large enough to fit your tart pan. Transfer the dough to your tart pan and lightly press into the bottom and sides. Let the extra dough hang off the edge, then take your rolling pin and press along the edge of the pan to take off the extra dough.
Cover the dough in plastic and place in the freezer.
Move your oven rack to the lower third of the oven and preheat to 400°F.
Peel and cut apples into 1/8” thick slices.
When the oven is ready, take the crust out of the freezer. Take the almond paste, lightly spread and press it to the bottom of the crust so it covers the entire surface.
Arrange the apple slices on top of the almond paste. Brush the melted butter all over the apples. Mix the sugar and cinnamon together and sprinkle on top.
Bake for 50 minutes.
Let cool on a wire rack before serving.