Bring the butter and eggs to room temperature. Mix together the dry ingredients. Finely chop the chocolate.
Make the tart crust. Beat the butter with a whisk, add the powdered sugar, and mix. Add the egg yolk and mix.
Sift the dry ingredients into the bowl and fold with a rubber spatula. It should become crumbly.
Press the dough together with the palm of your hands. Squeeze it together, but don't knead.
Wrap with plastic wrap and chill in the refrigerator for at least an hour. Make the cream with the same bowl and whisk without washing either.
To prepare the almond cream, beat the butter with a whisk, add the castor sugar and mix. Add the egg a little at a time, mixing with each addition.
Sift the dry ingredients into the bowl and mix. Melt the chocolate over a double boiler and pour into the bowl. Add the heavy cream, too, and mix together. Chill in the refrigerator for 30 minutes.
You can complete the steps up until here the day before, if you like.
To prepare the pan, melt some butter (amount separate from listed ingredients) and brush over the pan's surface. Chill in the refrigerator.
Use a tea strainer to dust the pan with flour, using a soft brush to brush off the excess. Chill in the refrigerator until just before ready to bake.
Take the almond cream out of the refrigerator. While waiting for the cream to soften a bit, prepare the cookie crust.
Line your working surface with plastic wrap and place the crust dough on top. Sandwich with another piece of plastic wrap. Roll the dough out to a 3 mm thickness, turning the dough every so often to spread it evenly.
To get the thickness right, place a 3 mm thick board or stick on each side while rolling it out. You can get them at home improvement stores.
Use the wrap to transfer and press the dough into the tart pan. Lightly press it into the edges with your fingers.
Cut off the excess dough. You'll bake the leftover dough later, so roll it up into a ball, wrap with plastic wrap, and chill in the refrigerator.
Poke holes into the dough. Poke a good amount.
Fill the tart with the chocolate almond cream and smooth the top. Arrange the almond slices on top and press down lightly with your hand. Chill in the refrigerator.
Preheat the oven. Bake at 180 for 45 minutes. Place into the oven directly from the refrigerator. Once baked, let cool in the tart pan on top of a cookie rack. Once cooled, remove from the pan.
Brush some marmalade jam on top for a glossy finish. If you don't like it tart, dust with cocoa powder instead.
Try my related recipe "Strawberry Amandine Tart"
Try my other related recipe "Matcha Chocolate Amandine Tart"