Preheat the Oven: Preheat your oven to 180°C (static) or 170°C (fan-assisted). Grease and line a 20 cm × 10 cm loaf pan with baking paper.
Prepare the Pound Cake Batter: Sift the flour and baking powder together in a bowl. In a separate bowl, whip the softened butter and sugar together until light and fluffy.
Add the Eggs: Add one egg at a time to the butter mixture, whisking constantly to fully incorporate each egg.
Combine Flour and Milk: Alternately add the flour mixture and milk to the batter, starting and ending with the flour. (Order: flour, milk, flour, milk, flour). Mix until smooth. Add the vanilla extract and a pinch of salt, and stir until combined.
Assemble the Cake: Pour the batter into the prepared loaf pan and level the surface. Sprinkle blueberries over the top of the batter.
Prepare the Crumble Topping: In a small bowl, mix the flour, cold butter, and sugar together using your fingers or a pastry cutter until the mixture forms small crumbs. Scatter the crumble topping over the blueberries.
Bake: Bake for 1 hour. Check the cake with a toothpick—it should come out moist but not wet. If needed, bake for an additional 10 minutes.
Cool and Serve: Allow the cake to cool in the pan for 10 minutes, then transfer it to a wire rack to cool completely. Enjoy!