Tomorrow (Sunday) is the last day you can buy oliebollen and krentebollen (=oliebollen with raisins) from the oliebollen stand at the end of the Grote Marktstraat next to the Blokker and Xenos stores.
This is our Marco, Roger and I’s favorite place to get oliebollen and apple beignets. Usually they close every year by 15 January, however this year the city granted them a permit extension through the end of January. They were also able to open a month earlier due to most carnivals not being able to open during 2020 (the same was true for all oliebollen stands in the area).
Check out their official website.