Prepare the Pastry Crust:
In a mixing bowl, combine the flour and powdered sugar. Add the cubed butter and rub together until the mixture resembles coarse crumbs.
Add the egg yolk and 1 tablespoon of cold water, mixing until the dough comes together. If needed, add a little more water.
Roll the dough into a ball, wrap in plastic wrap, and refrigerate for 30 minutes.
Roll Out and Blind Bake the Pastry:
Preheat oven to 350°F (175°C).
Roll the chilled dough on a lightly floured surface and fit it into the tart pan. Trim the edges, prick the base with a fork, and line with parchment paper. Fill with pie weights or dried beans.
Bake for 15 minutes, remove weights and parchment, and bake for another 5-8 minutes until the crust is lightly golden. Let it cool.
Assemble the Filling:
Spread the raspberry jam evenly over the bottom of the cooled crust.
In a bowl, cream the butter and sugar together until light and fluffy. Beat in the eggs one at a time, followed by the almond flour, all-purpose flour, and almond extract until smooth.
Bake the Tart:
Spread the almond mixture over the jam in an even layer. Sprinkle the top with sliced almonds.
Bake for 30-35 minutes, or until the filling is set and golden. Allow the tart to cool completely on a wire rack.
Add Icing (Optional):
Mix the powdered sugar with water to make a thick icing. Drizzle over the cooled tart and garnish each slice with a maraschino cherry, if desired.