Step 1

Combine the butter and both sugars in a mixer. Cream until very light. Combine the cinnamon, salt and flour; add all at once and beat on medium just until large crumbs form.

Step 2

Scrape down the sides and the bottom for unincorporated flour. Mix briefly. Do not over mix or you will end up with a really thick cohesive mixture. Store the crumbs in the refrigerator while you make the cake.

Step 3

Preheat the oven to 325°F. Line a 9x13 inch pan with parchment. Spray under the parchment to hold it in place and spray the parchment and sides of the pan. Set aside.

Step 4

Whisk together the flour, baking soda and salt in a medium bowl. Without cleaning the bowl in which the crumbs were made, beat the butter and sugar on medium speed until pale and fluffy.

Step 5

Beat in eggs one at a time and then the vanilla.  If it curdles, that's fine.

Step 6

Add flour alternating with buttermilk, beginning and ending with flour. Beat until well combined.

Step 7

Spoon batter into pan and spread evenly using an offset spatula. Spread the crumbs evenly over the batter.

Step 8

Bake until golden brown and a cake tester inserted into the center comes out clean, about 45 minutes.

Step 9

Transfer the crumb cake to a rack and cool about 15 minutes. Dust with powdered sugar. This crumb cake also freezes well.  Just wrap it well and freeze.

Step 10

This crumb cake also freezes well.  Just wrap it well and freeze. To use, I would recommend unwrapping it and thawing it completely first. Rewrap it in foil and reheat it in a 350 degree oven for 15 to 20 minutes - just to warm it all the way through.