Instructions

1. Gather all ingredients.
2. Preheat the oven to 350 degrees F (175 degrees C). Grease and flour an 8.5-inch springform cake pan; set aside.
3. Stir together flour, oats, baking powder, baking soda and salt in a bowl. Set aside.
4. Place 1/2 cup of sugar into a separate bowl. Finely grate in zest of 2 lemons and rub lemon zest into the sugar to help release its flavor.
5. To the lemony sugar, add the yogurt, melted butter, and egg. Squeeze in 1 tablespoon of lemon juice (around 1/2 a lemon). Whisk well to combine.
6. Add flour mixture to the wet mixture and fold together until just combined.
7. Spoon half of the cake batter into the prepared pan, spread out into an even layer, and scatter on 1/2 of the blueberries.
8. Dot the remaining batter on top and spread out to cover the blueberries. Scatter remaining blueberries on top and press down gently to push them into the batter. Sprinkle with remaining 1 tablespoon of granulated sugar.
9. Bake in the preheated oven for 40 to 50 minutes if using fresh blueberries or 50 to 60 minutes if using frozen. The cake is done when it looks golden all over and a skewer inserted into the center of the cake comes out with a few moist crumbs stuck to it. Allow the cake to cool in the pan for 10 minutes before removing and serving.