Just a sample site of a possible usage of DateTimeExtensions nuget package.
January 01 New Year
April 05 Good Friday
April 07 Easter
April 08 Easter Monday
April 27 Kingsday
May 05 Liberation Day
May 16 Feast of the Ascension
May 26 Pentecost
May 27 Pentecost Monday
December 25 Christmas
December 26 Boxing Day
DateTimeExtensions DateTimeExtensions