Finland does not have high-star Michelin restaurants, while we do have few in Helsinki, but I would recommend to check "Kaskis" in the pictoresque old capital city Turku which is 1,5 hours drive west of Helsinki.

It just got a Michelin sticker recommendation and it is in my opinion the best restaurant in Finland nowadays. It is fully booked though for months in advance so the best you can do is to pick their telephone number in the internet and call if they have any last minute cancellations.