Peel the potatoes and cut them into uniform small pieces/cubes. About 3x3 cm.

Boil them in salted water until tender. This takes about 18-23 minutes.

Coarsely mash the potatoes with a potato masher or fork.

Cut the butter into smaller pieces and add it to the potatoes, stirring well.

Repeat the process with the egg yolks, and once you have a uniform mixture, season to taste. It may need a little salt or pepper from a grinder, and you can add some thyme if desired.

Put your mashed potatoes in a piping bag fitted with a star nozzle.

Pipe the potato mixture onto a parchment-lined baking sheet.

Create the patterns you desire and be as creative as you like.

Place the baking sheet in the oven and bake at 200 degrees Celsius (392 degrees Fahrenheit) (fan) for 10-15 minutes. The mashed potatoes are cooked, so the goal is solely to get a bit of color on them. Thus, you can make the mashed potato mixture in advance and store it in the refrigerator until needed.

In that case, you just need to give them a bit more time in the oven.

Bon appétit.