Preheat your oven to 350°F.

Mix the dry ingredients in a large bowl: flour, sugar, baking powder, and salt.

Cream the butter and sugar in a separate bowl until light and fluffy.

Add the eggs one at a time, mixing well after each addition.

Combine the wet ingredients—milk and vanilla—with the creamed mixture.

Prepare the crumb topping by mixing flour, sugar, cinnamon, and cold butter until crumbly.

Spoon half of the batter into a greased baking pan, then sprinkle half of the crumb topping on top.

Bake in the preheated oven for 30-35 minutes or until a toothpick inserted into the center comes out clean.

Cool completely on a wire rack before slicing into squares.