Egg yolk sizes changed over the years?
Hello @Dudie and welcome to Seasoned Advice. Regarding the size of egg yolks in certain size eggs, you may find this interesting. Here is the link to the  page .


  A change in the feed given to chickens has resulted in healthier eggs but the trend for buying larger eggs has led to there being less yolk to white.
  This is because of the preference for bigger eggs now compared with 30 years ago. The size of the yolk remains the same in a large egg as in a medium one, with larger eggs simply containing more white.


Looking at recipes for Norwegian cookies, I think that the recipe you are using is more widely known as Norwegian Butter Cookies. I found several using the same ingredients and they seem to be pretty consistent. The variations I found were mostly in preparation. E.g., one said to cream the butter and egg yolks together while another said to sieve the egg yolks.

The recipes I found for Norwegian Crowns used both cooked egg yolks and raw egg yolks (with the exception of one recipe that was nearly identical to all of the butter cookie recipes except that it called for vanilla).

So, in light of the information, I would offer these suggestions:


Stay with the eggs you are using. If you think you need more, add more. If you think you need less, use less.
You might give a look to other recipes and try a different prep method, e.g. creaming the egg yolks and butter together.
As I saw in several recipes you can use a cookie press or use a drop method. If you use a ball or drop method you can use a fork to press in a criss-cross pattern. See pic below.