"A huge thank you to all our customers near and far who have supported the shop over the years," said the team in a social media post this week.
"We are thankful to so many people (too many to name all). We would like to give a mention to Oban school pupils who have been a great support over the years. Be proud of all your children. We never had a difficult day in 19 years."
The family-run bakery in Gibraltar Street employs Sylvia's husband Heinz and son Michael downstairs, with Sylvia serving upstairs, plus five members of staff.
Amid the busy stream of customers, The Oban Times managed to catch Sylvia for a few minutes to find out about their plans.
"It is time," she said: "My husband is 70. I will be 70 next year. It has not been an easy decision.
"We decided in January. We discussed it with all the staff. They have all been offered jobs. In Oban we have no problem: everyone is crying out for staff.
"We are right down to the bare bones. We have been rushed off our feet. It has been emotional over the last few weeks. I am happy about retiring, but I am sad about leaving my customers and the staff.
"We have had lots of great staff over the years, some of them staying friends. We have had wonderful customers. What more can you ask for?
"We have had super memories. We ran the half marathon in Edinburgh - three of the girls and myself. We ran for Oban Hospice and raised £3,000. We have always been well supported by the community.
"It has been a well-loved shop, and it still is. We are going to lease the shop. It is not like it is going to disappear. There are a few people interested. We will support whoever is getting the business to get them up and running."
Before opening Bossards in Oban in 2005, the couple had two shops in Edinburgh, where Heinz was a manager at Flour Power for 10 years. He comes from a Swiss family of bakers - in fact, you can still visit Bossards bakeries in Zug near Zurich.
Sylvia and Heinz plan to spend more time with their grandchildren, travelling, and chilling. Michael, one of their three children, has been working at Bossards since he was 16. He is now 39. He and his partner are heading abroad for new adventures.
What will they be doing on Monday morning? Sylvia replied: "Coming in to clean up!"
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