Start by mixing flour, sugar, almond powder, salt, egg, and butter in a mixing bowl. Knead this into a nice ball of dough. Once smooth, wrap it in plastic foil and let it cool down in your fridge for at least 1 hour.

Meanwhile, mix almond powder, sugar, flour, eggs, and butter. Cut the vanilla pod open, scrape out the seeds, and add them to the batter along with the zest of lemon. Mix everything together well, then transfer the mixture into a piping bag and set aside.

Flour your workspace and use a rolling pin to roll out the dough until it is about 3 millimeters thick. Use your baking tin (One standard 9-inch (22–24 cm) tart pan with a removable bottom or springform mechanism.) to cut out the bottom shape, then grease the tin with butter or baking spray. Place the bottom in the tin, cut the remaining dough to fit the sides, and press it firmly into place. Let the lined tin rest in the fridge for at least 30 minutes.

Mix the juice of lemon with water in a bowl. Quarter and core apples, making sure the pieces are evenly sized. Thinly slice the apple quarters using a mandolin, and drop them into the lemon water. Let them sit for at least 10 minutes to prevent browning, then strain the water.

Pipe the frangipane evenly onto the bottom of the chilled dough. Arrange the apple slices starting from the outer edge, slightly overlapping them and working your way towards the middle. Bake in a preheated oven at 170°C (338°F) for about 40 minutes until golden brown.

Take the apple pie out of the oven and immediately brush the top with melted apple jam using a pastry brush for a beautiful glossy finish.