Step 1

Preheat oven to 325F. Spray and flour a quarter sheet pan (9 x 12 1/2)

Step 2

To make the crumb topping put the flour, sugar, and cardamom in a bowl. Add the melted butter and stir briefly with a spatula, then go in with your hands and toss the mixture together until everything is evenly moistened and you get large crumbs. Break any big chunks apart with your fingers as you toss. Once it is all evenly combined, set aside.

Step 3

Put the sugar and orange zest in a food processor and process until the zest is completely incorporated and the sugar is moist and orange. Pulse the machine to make sure there are no chunks of zest left.

Step 4

Put the orange sugar, oil, egg, milk, and extract in a bowl and whisk together.

Step 5

In another bowl whisk together the 1 1/2 cups flour, baking powder, and salt.

Step 6

Add the dry mixture to the wet and blend gently with a spatula.

Step 7

Spread the batter into your prepared pan. It will be a thin layer, but spread out as evenly as you can.

Step 8

Top the batter with the crumbs, breaking up any large crumbs with your fingers. Be sure to get them evenly scattered, and don't forget all the edges and corners. You don't want a big mound in the middle.

Step 9

Bake for 30-35 minutes, or until a toothpick inserted in the center comes out clean. Rotate the pan halfway through cooking.

Step 10

Let the cake cool on a rack for 15 minutes, then dust with powdered sugar. Enjoy warm, or at room temperature. This crumb cake is best the day it is made, but will keep on the counter, covered, for a couple of days.