This delicious, lightly-sweet, half-whole-grain coffee cake is moist and fluffy, with a light covering of streusel topping it.
Place ½ cup oats on a baking sheet. Bake at 350F for 6-8 minutes, until light brown, while you preheat your oven. Keep an eye on them at 6 minutes to be sure they don't scorch. Set aside and cool slightly.
Grind oats in a food processor or bullet blender, for about 4-5 seconds or until finely ground. Combine ground oats with flours, baking powder, baking soda, and salt in a medium bowl.
Using an electric mixer or stand mixer, beat butter with sugar and brown sugar until light and fluffy, about 3 minutes at medium speed. It may only become creamy if your kitchen is cool; that's okay.
Add eggs, one at a time, then add vanilla. Mix until combined.
On low speed, add half of the flour mixture, and stir until combined. Mix in the sour cream, then add the remaining flour mixture. Scrape down the sides and bottom of the bowl, and mix until just combined.
Spoon batter into a greased 9-inch springform pan. Spread it out to edges. Set the pan side while you make the streusel.
Melt the 1 tablespoon butter if you haven't already. This should take no more than 20-30 seconds in the microwave.
Stir the ¼ cup brown sugar and cinnamon into the melted butter. Add the ¼ cup oats and the nuts; stir until everything is sandy and well-mixed.
Sprinkle the streusel on top of the batter in the Springform pan, getting it all the way to the edges.
Bake at 350F for 30-35 minutes, until a toothpick inserted into the center comes out clean. Cool cake for 10 minutes, then remove the sides of the Springform pan.
Serve warm. If kept well covered, cake is almost as good the next day.
Both old-fashioned and quick oats work here; instant and steel-cut oats will not.
This coffee cake is half whole grain. I don't recommend making it 100% whole grain because whole wheat flour is heavier than all-purpose. However, if you want to attempt it, be sure to choose White Whole Wheat Flour to keep the taste from being too heavy.
Choose margarine instead of butter and light sour cream instead of whole-milk sour cream, if desired; that's how Cooking Light Magazine originally developed it.
Any chopped nut will work in place of walnuts; pecans would be best. To accommodate a nut allergy, substitute 2 tablespoons additional oats for the nuts in the streusel.
Adapted from Cooking Light Magazine
Originally written in 2010 and updated in March 2018, with more updates in 2023.
Calorie count was calculated in MyNetDiary and is an estimate only.