Sift together the all-purpose flour, powdered sugar, and almond flour in a bowl.

Cream the room-temperature unsalted butter with kosher salt, then gradually incorporate the dry ingredients and eggs until a smooth dough forms.

Chill the dough for at least 2 hours to firm up.

Roll out the chilled dough on a lightly floured surface until it's about ⅛ inch thick.

Fit it into a tart pan, trim the edges, and chill again.

Blind bake in a preheated oven at 325°F for about 30–35 minutes, or until golden brown.

Peel and chop the Granny Smith apples into bite-sized pieces.

Sauté them in a pan with a bit of butter and dark brown sugar over medium heat until caramelized.

Stir in lemon juice, cinnamon, nutmeg, and cardamom, then set aside to cool.

In a mixing bowl, combine the flour, dark brown sugar, and spices.

Cut in cold butter until the mixture resembles coarse crumbs.

Stir in maple syrup and sliced almonds, then chill the topping in the fridge.

Spread the cooled apple filling evenly over the baked tart crust.

Scatter the chilled crumble mixture generously on top.

Place the assembled tart back in the oven and bake at 350°F for 20–25 minutes until golden brown.

Let cool for about 30 minutes before slicing and serving.