This walnut oatmeal sweet Irish soda bread recipe yields a lightly sweet soda bread, with a rich nutty flavor and a dense yet soft texture that pairs perfectly with a creamy slathering of butter. Try it as a meal side or as breakfast with a hot cup of coffee or tea!
In a small mixing bowl, stir together the buttermilk and 2 cups of the rolled oats. Set aside for one hour to soften. Toast the walnuts in the oven while the oats are soaking. (See: How To Roast Walnuts for step-by-step instructions.)
Adjust oven rack to lower-middle position; heat oven to 400℉.
Whisk together the all-purpose flour, cake flour, whole wheat flour, remaining ½ cup oats, brown sugar, baking soda, cream of tartar, and salt. Use your fingers to work the 2 tablespoons of softened butter into the flour mixture, until it resembles coarse crumbs.
Add the oatmeal/buttermilk mixture and toasted walnuts to the flour mixture, and stir with a fork until combined. You may need use your hands to work it all together.
Knead the dough on a lightly floured surface or baking mat just until the mixture comes together but is still slightly bumpy. Kneading it until it's smooth will overwork the dough and make your bread tough.
Form the dough into a 6-inch disc that is about 2 inches high. Using a serrated knife, cut an X in the top of the disc. If desired, brush with a bit of additional buttermilk and sprinkle a small handful of oats over the top.
Bake at 400℉ in a cast iron pan or on a parchment-covered baking sheet for 45-55 minutes, until a toothpick inserted in the center comes out clean. If the bread starts to brown too much, a piece of foil tented over the top will prevent further browning.
Remove the bread from the oven, and while it's still hot, brush the top with the melted butter. Cool for 15-20 minutes before slicing. Serve warm with Irish butter or try making your own homemade butter. (See: How To Make Butter From Heavy Cream for step-by-step instructions.)
Recipe Notes
Storage: Leftovers can be stored wrapped tightly in aluminum foil or plastic wrap at room temperature for up to 4 days or in the freezer for up to 3 months.