Spread the beets one by one on pieces of foil, add a little salt and wrap them. Place them in a pan and bake at 180 degrees for about an hour.
When their temperature drops, peel them and pass them through a coarse grater.
In a square pan, spread a sheet of puff pastry and press well on the edges to get the shape of the pan.
Remove the excess edges and pierce the sheet with a fork. Bake in a preheated oven at 180 ° C for 20 minutes.
Fry the bacon in a pan and add the beetroot.
Add the nutmeg, thyme, balsamic and salt.
Take the base as soon as it cools, carefully remove it from the pan, turn the pan upside down and place the base of the tart on top.
Pour the filling and spread evenly.
Break the nuts by hand and spread on the tart.
In a bowl, grate the cheeses, add the yogurt, yolk, pepper and mix.
Distribute the cheese all over the surface of the tart and spread (optional) pieces of beetroot, a little olive oil and salt.
Bake again in a preheated oven at 180 °C for 20 minutes.
Allow to cool a bit, cut and serve.