In a mixing bowl, combine all-purpose flour, almond flour, and sugar. Add the cold butter and mix until it resembles coarse crumbs.
Add the egg yolk and cold water. Mix until the dough comes together. Press the dough into a tart pan and bake for 15 minutes.
For the filling, heat the heavy cream in a saucepan until it just begins to simmer. Remove from heat and add the chopped dark chocolate. Stir until smooth.
Add sugar, vanilla extract, and salt to the chocolate mixture. Pour the filling into the baked crust.
Sprinkle toasted sliced almonds on top. Chill in the refrigerator for at least 2 hours before serving.