Preheat the oven to 375 degrees F (190 degrees C).
Combine flour and sugar in a bowl. Cut in butter until the mixture resembles coarse crumbs.
Combine egg yolks and milk in a small bowl; stir into flour mixture until dough is blended.
Press dough, using lightly floured hands, into the bottom and 1 inch up the sides of a 12-inch tart pan with a removable bottom. Line the unpricked shell with a double thickness of aluminum foil. Place pan on a large baking sheet.
Bake in the preheated oven until edges are lightly browned, 12 to 15 minutes.
Meanwhile, combine condensed milk, maple flavoring, cinnamon, and salt in a medium bowl. Stir pecans, walnuts, and almonds into the batter.
Remove shell from the oven, leaving oven on, and fill with batter.
Return tart to the oven and bake until golden brown, 20 to 25 minutes.
Remove from the oven and cool completely on a wire rack, about 30 minutes.
Place chocolate chips in a microwave-safe bowl and heat in a microwave oven until melted, 1 to 3 minutes. Drizzle tart with melted chocolate. Refrigerate until chocolate has hardened and filling is firm.