Icelandic Happy Marriage Cake

May 25, 2020
Piece of Icelandic Happy Marriage cake on a plate with an orange-striped napkin the background

This post was originally published in July 2015 and was updated in May 2020.

My love for Minnesota summers is a bittersweet affair, marked by the ever-present knowledge of an impending separation.  Slurping  down ice cream from Sebastian Joe's and the Grand Ole Creamery, laying on a picnic blanket by the Mississippi River, eating sauteed CSA zucchini on our patio, walking around Lake Harriet, picking pounds and pounds of strawberries—the finite number of blissful summer moments makes each one more heart-achingly lovely than the last. 

Since Minnesota summers are so short, you need to start celebrating them early—and that's where my recipe for Icelandic Hjónabandssæla, or happy marriage cake, comes in.  The rhubarb filling makes it a perfect early summer dessert for cool climates, when sturdy rhubarb is the only produce you can rely on.   

Top down view of a cake in square glass baking dish with two pieces removed

The oatmeal-based cake has a texture similar to my fudge oatmeal bars, denser and much firmer than a traditional flour-based cake.  The rhubarb filling is tart, and the cake has a subtle sweetness, making it eminently suitable for breakfast or a mid-morning coffee break.  Tightly covered, it keeps quite well for several days in the refrigerator.

Rhubarb filling adapted from Outside Oslo; cake adapted from Iceland Review

Yield: one 8 inch by 8 inch square cake


Rhubarb filling ingredients on a baking sheet

Rhubarb Filling

  • 3 cups chopped rhubarb (1/2 inch pieces, about 3 medium stalks)
  • 1/4 cup granulated sugar
  • 1 teaspoon vanilla
Icelandic Happy Marriage Cake ingredients on a baking sheet


  • 1 3/4 cup quick oats
  • 1 3/4 cup all-purpose flour
  • 1/2 cup granulated sugar
  • 1 teaspoon baking soda
  • 14 tablespoons (1 stick plus 6 tablespoons) unsalted butter, softened
  • 2 eggs
  • Rhubarb Filling (recipe above)
  • whipped cream or vanilla ice cream, for serving (optional)

Rhubarb Filling
Combine the rhubarb, 1/4 cup sugar, and vanilla in a medium saucepan.  Cook over medium heat, stirring occasionally, until rhubarb has completely broken down, about 25 minutes.  Reduce heat if rhubarb starts sticking to the saucepan.  Remove from heat and cool completely.

Rhubarb filling in a saucepan


Preheat oven to 400 degrees Fahrenheit.

Mix the oats, flour, 1/2 cup sugar, and baking soda in a large bowl until well-combined.  Mix in the softened butter until evenly incorporated.  Add the eggs and mix until a crumbly dough forms.

Grease an 8 inch by 8 inch baking dish using the wrapper from the stick of butter.  Evenly press about 2/3 of the dough into the prepared dish.

Bottom layer of Icelandic Happy Marriage Cake in a glass dish

Evenly spread with the prepared rhubarb filling.

Bottom layer of Icelandic Happy Marriage Cake spread with rhubarb filling

Roll a piece of the remaining dough into a ball about 1 inch in diameter and flatten it between hands.  Place the piece of flattened dough on top of the rhubarb filling.  Continue in this manner, using smaller pieces of flattened dough to fill in the gaps between the larger pieces, until the rhubarb filling is completely covered.

Icelandic Happy Marriage Cake before baking

Bake for 20 minutes, or until the top of the cake is lightly browned.

Once cake has cooled completely, store tightly covered in refrigerator.  Reheat before serving, with whipped cream or vanilla ice cream if desired.

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Top down view of Icelandic Happy Marriage Cake in glass dish with text reading "Icelandic Happy Marriage Cake"