1. Preheat your oven to 350°F (175°C). Grease and flour a 9×9-inch baking pan or line it with parchment paper.

2. In a small bowl, prepare the crumb topping by mixing 1/2 cup flour, 1/3 cup brown sugar, 1 teaspoon cinnamon, and a pinch of salt. Cut in 1/4 cup cold butter until it resembles coarse crumbs. Chill until ready to use.

3. In a medium bowl, whisk together 2 cups flour, 2 teaspoons baking powder, 1/2 teaspoon baking soda, and 1/4 teaspoon salt.

4. In a large bowl, cream 1/2 cup softened butter with 3/4 cup sugar until light and fluffy (2–3 minutes).

5. Beat in 2 eggs, one at a time. Add 1 cup Greek yogurt and 1 teaspoon vanilla extract. Mix until smooth.

6. Add the dry ingredients in two parts, alternating with 1/4 cup milk. Stir gently and don’t overmix.

7. Fold in 1 1/2 cups blueberries. If using frozen, toss in a little flour to prevent sinking.

8. Pour batter into the prepared pan. Sprinkle crumb topping evenly over the top.

9. Bake for 40–45 minutes or until a toothpick inserted in the center comes out clean.

10. Let the cake cool in the pan for 20 minutes before slicing and serving.