1. Preheat oven to 350°F (175°C) and grease or line an 8×8-inch pan.

2. In a bowl whisk together 1 1/2 cups flour, baking powder, and 1/2 teaspoon salt.

3. In another bowl cream 1/2 cup softened butter and 1 cup sugar until light and fluffy.

4. Beat in eggs one at a time, then stir in vanilla and sourdough discard until smooth.

5. Alternate adding the dry mixture and milk, mixing gently until just combined.

6. In a separate bowl combine brown sugar, 1/2 cup flour, cinnamon, and pinch of salt, then cut in cold butter until coarse crumbs form.

7. Pour batter into the prepared pan and sprinkle the cinnamon crumble evenly over the top.

8. Bake 35–45 minutes until golden and a toothpick comes out with a few moist crumbs. Cool 15–20 minutes before slicing.