Preheat your oven to 180°C (355°F).
Stick the muffin tin in the oven to warm up.
Wash and peel the potatoes.
Slice them finely on the mandolin. You want to be able to bend them so the ends can touch without breaking.
Remove the muffin tin from the oven.
Divide the butter into ten equal cubes and place one in each void.
When the butter is melted and spread out in the bottom of the pan, start to layer the potato slices. You want the larger pieces at the bottom. Add a sprinkle of sea salt every five layers and spread them out as much as possible.
When you have layered the potatoes almost to the top of the pan, start using the smaller slices and arrange these so they overlap. Push them down along the edges to get that closed rose shape.
Finish with 5-6 overlapping pieces, leaving a small gap at the top.
Mix the cream, minced garlic, mustard, sea salt, pepper, and thyme.
Pour spoonfuls of the cream mixture on top of each potato stack until you can see the cream at the top. You may need to go back and refill a few times.
Bake in the oven for around 35 minutes until golden and crisp.
Allow to set for 15-20 minutes (this helps them hold their shape).
To remove the potatoes from the pan, use a knife to loosen them from the edge, and then lift them carefully with a spoon.
Sprinkle with fresh chopped spring onions or thyme.