Step 1

Preheat oven to 325°F and grease and flour an 8-inch springform or cake pan. Line the bottom of the pan with parchment paper and set aside.

Step 2

In a small bowl, make the crumble topping. Stir together the melted butter, 3/4 cup flour, 1/3 cup sugar, lemon zest, and salt. Set aside.

Step 3

In a large mixing bowl, cream together the butter, sugar, and lemon zest with an electric mixer until light and fluffy.

Step 4

Add the eggs, vanilla, lemon juice, salt, and baking powder and beat until combined.

Step 5

On low speed, add half of the flour and mix until combined. Add sour cream and mix until combined, followed by the remaining flour, and then the milk.

Step 6

Pour batter into prepared pan and sprinkle with crumble topping, leaving some larger chunks.

Step 7

Bake until top is a light golden brown and a toothpick inserted into the center comes out clean, about 40 minutes.

Step 8

Cool on a wire rack at least 30 minutes before serving. Dust with powdered sugar to serve, if desired. Enjoy!