Beat butter and sugar together until light and fluffy.
Add eggs, one at a time, beating until fully incorporated.
Add dry ingredients, milk and raisins. Stir to incorporate.
Pour the batter into a greased loaf pan. Bake for 45 to 55 minutes at 325 F (170 C).
Allow the Jólakaka to cool completely before cutting.
Notes
Jólakaka is best the 2nd day, so bake the Christmas cake a day ahead to enjoy the following morning with coffee.I've since read that recipes add 1/2 tsp lemon extract, or 1 tsp of lemon zest. I think that would be lovely in this cake, and I'm going to add it next time.