Add the butter, granulated sugar, cinnamon, brown sugar, vanilla sugar, salt, egg yolk, flour, and baking powder to a deep bowl. Mix/knead all the ingredients together into a cookie dough. Place the dough in the refrigerator for a while to firm up. This will make it easier to roll out the cookie dough later.
Put the pecans, sugar, and egg into a mixer. Mix until smooth. Put the pecan filling into a piping bag.
Grease the baking rings. Sprinkle some flour on the work surface and roll out the dough (thickness should be about 1 to 1.5 cm). Cut out the cookie dough with the baking ring, ensuring the dough stays in the ring. Place the baking ring with the cookie dough on a baking sheet lined with parchment paper. Repeat the process with the remaining baking rings. Pipe some of the pecan filling into the cookie dough, leaving 1 cm of space around the edges.
Place in a preheated oven at 175°C for about 18 to 25 minutes.
Let the pecan tarts cool completely.
Pour the unwhipped cream into a saucepan and bring it just to the boil. Remove the pan from the heat and add the chocolate drops. Let it sit for a minute. Stir together until smooth. Allow the ganache to cool completely.
Whip the unwhipped cream together with the vanilla sugar, sugar, and whipped cream stabilizer until stiff.
Add the ganache and mix it together until well combined. Transfer the cream mixture to a piping bag.
Pipe a nice tuft of the cream mixture onto each pecan tart.
Melt some cocoa drops and drizzle them over the pecan tarts. Place a pecan nut on each tart.