This is a delightful blueberry crumble cake you’ll be proud to serve family and friends. Moist as can be, with a tender buttery crumb, sweetened with juicy blueberries, and a sweet cinnamon crumble topping. Don’t miss out on the lemon glaze - it’s utterly scrumptious!
In a small saucepan set over medium heat, add blueberries, lemon juice, lemon zest, sugar and cinnamon. Give it a couple of stirs to mix well. Cook the mixture until the blueberries release their juices and soften a bit, stirring only occasionally. Tip the cooked blueberries into a strainer set on top of a bowl to catch the juices. Set aside to cool to room temperature. Note: Do not over-stir or over-cook. Most of the blueberries should still look plump and juicy, not overly punctured and mushy.
Make the crumble topping
In a mixing bowl, stir flour, sugar and cinnamon together. Rub in cold butter cubes with your fingers until the mixture resembles coarse breadcrumbs, roughly the size of peas. Place in the chiller until needed.
Make the cake
Preheat oven to 190 deg C (375 deg F). Grease the sides and base of a 20-cm or 8-inch loose-bottomed cake pan. Line the base with baking paper.
In a stand mixer fitted with a paddle beater (or using handheld electric beaters), beat butter and sugars on medium speed until the mixture turns pale and feels light and fluffy, about 5 - 7 minutes.
Add lemon zest and beat for a few seconds to mix well. Then add lightly beaten eggs, a bit at a time. The batter will curdle at first. Continue to beat on medium speed until the batter becomes smooth again, before adding the next addition.
Sift in the plain flour, baking powder, ground cinnamon and salt. Fold a few rounds by hand first, before you start the mixer. Turn the mixer on low speed, and beat until just combined and the batter is smooth, about 5 - 10 seconds.
Add the milk and lemon juice, and beat until just incorporated. The final batter should be smooth and thick.
Fill the pan: spread a third of the batter into the prepared pan. Using a spatula, spread an even layer to cover the base. Gently drop spoonfuls of blueberry compote (drained of juices) over the batter. Spoon another one-third of the batter over the fruit, followed by the compote. Finish with the remaining batter and blueberry compote. Note: If using raw fresh or frozen blueberries, gently fold by hand into the batter before scooping out into the prepared cake pan. After filling the pan, level the surface with a spatula.
Take the crumble topping out of the chiller and spread evenly over the batter, all the way to the edges of the cake pan. Set the pan on the middle rack of the oven, and bake for 45 - 50 mins or until a bamboo or metal skewer inserted into the center of the cake comes out clean. If the skewer emerges with some sticky batter, bake for a few more minutes and check again. When baking is finished, remove the cake from the oven and leave it in the pan for 10 minutes.
Then remove from the pan, and set the cake onto a wire rack to cool a while. Meanwhile, make the lemon glaze.
When the cake is cooled enough, drizzle the lemon glaze with a metal spoon over the top and sides of the cooled blueberry cake as desired. This cake is best served warm.
Make the lemon glaze
In a small bowl, combine icing sugar, lemon juice, melted butter and salt. Stir vigorously until the glaze is smooth. Note: If the glaze starts to firm up too soon, microwave on low power in short bursts until its at a pourable consistency.