According to "Cooks Illustrated", you are to roll the topping into large pea-sized balls and scatter over the cake dough, making it even, with no large clumps. That makes the crumbs. Well, I'm too impatient for that, so I had to find another way to make this fully incorporated topping, crumbly! I didn't want to spend a lot of time rolling sugar balls for the topping! Have I mentioned that I'm somewhat lazy? Well, I found a way to crumble the topping. You must stir up the topping ingredients first, that way when you are ready to top the cake, the butter laden topping will be somewhat set, and can be crumbled.
Take a fork and "rake" it side ways across the topping and it will gradually crumble into small pieces. Don't try to do it too deeply, just in layers. Then take a spoon and scoop up the crumbs and scatter over the cake. Then repeat the raking until all the crumbs are made. This didn't take near as long as the original way required and it resulted in small crumbs, which made this lazy baker very happy! And as you can see from the photo, the topping didn't have any huge chunks, but a nice looking topping that was crisp and delicious! My only adaption to this recipe was to use light brown sugar instead of dark brown sugar called for in the recipe. You've got to give it a try!
slightly adapted from Cooks Illustrated
CRUMB TOPPING: make this first
1/3 cup granulated sugar (2 2/3 ounce)
1/3 cup light brown sugar- original recipe calls for dark brown sugar
1 teaspoon cinnamon- recipe calls for 3/4 teaspoon
1/8 teaspoon table salt
8 tablespoons melted, unsalted butter
1 3/4 cup cake flour (7 ounces)- no substitutes
1 1/4 cup cake flour (5 ounces) - no substitutes
1/2 cup granulated sugar
1/4 teaspoon baking soda
1/4 teaspoon table salt
6 tablespoons unsalted butter, softened, but still cool
1 teaspoon vanilla
1 large egg
1 egg yolk
1/3 cup buttermilk - (plain yogurt may be substituted)
Confectioners sugar for dusting
1. For topping: Mix sugars, cinnamon, salt and melted butter together. (Don't use real hot butter, let it cool some). Add flour and mix with a rubber spatula or wooden spoon until ingredients are fully incorporated. Mixture will be smooth, not crumbly. Set aside.
2. For cake: Place oven rack in upper middle oven position and preheat oven to 325 degrees. If desired, cut a piece of parchment 7 inches wide and 16 inches long to fit in pan. Spray a 8x8 inch baking pan with cooking spray. Fit the parchment evenly into the pan with the long sides hanging evenly. Spray parchment with cooking spray. You only need to use parchment if you plan to take the whole cake out of the pan to serve. I left my cake in the pan, so I didn't follow this step.
3. In a large bowl combine flour, sugar, baking soda and salt. With a mixer, blend in the butter on low speed, 1 tablespoon at a time until you cannot see any pieces of butter. Add the butter, egg, egg yolk, vanilla and butter milk and mix on medium speed, about 1 minute until completely blended and fluffy.
4. Pour cake batter into the prepared baking pan and smooth evenly. Take a table fork and "rake" the topping, so it will form crumbs. Spoon them on the cake. Or, you can roll the mixture into balls if you want! Place in preheated 325 degree oven and bake for 35-40 minutes, until a toothpick inserted comes out dry. Cool cake completely. If using parchment, remove cake from pan to serve. Otherwise, just serve it from the pan. Enjoy!
NOTE: Using powdered buttermilk is not recommenced for this recipe. "Cooks" says that the batter will be too thin and the topping may sink.