I’m “imported” to Denmark, and guess what: so is the Danish easter ale tradition. As far as I’ve understood, the tradition started at the end of the 19th century when a few pubs in Copenhagen around easter would import double-bock beer called Salvator from the German order of Paulaner. This was a beer the monks had been allowed to sell since the 1780s. Whether it was actually the beer of the Paulaner monks is somewhat of a mystery, as this brand was so strong that all the Bavarian stouts were simply called Paulaner Salvator. Serving these beers turned out to be a huge success, so in 1905, Carlsberg, the big Danish beer brewery would make their own easter ale and sell it on tap. The year after, Tuborg, their arch rival, followed with their own easter ale on tap.
Today, there are many small breweries all around Denmark, and each brewery with respect for themselves will have their own easter ale. Some will have them a pinch lighter than a christmas ale, some will have a bottle of pure summer. Speaking of christmas ale, it’s actually the easter ale tradition that has given us the christmas beer tradition, not the other way around!