I use a pound cake mix for the cake. A regular cake recipe always turns out being too light. Well, for us anyway.Just follow the directions on the box. Spread the batter out in a 9"x13" baking pan. Well all of the directions except how long in the oven. We're going to cut it short and add the crumb mixture on top and then give it a little more time in the oven.
For the crumb topping
Using a hand or countertop electric mixer mix all of the dry ingredients together.I put the sticks of butter, with the paper wrapping still on them, in the microwave and soften them in 10 second zaps until they are almost melted. Then holding the paper wrapping let them slide into the bowl of the dry ingredients. Some folks just go ahead and take the paper off and melt the butter. Mix it all together. Here is where you will be glad that you have the electric mixer. You could do it with a whisk but the mixer makes it much easier.
Check on the cake when it has been in the oven for about a half hour. When it has risen up and the sides are just starting to want to pull away from the sides of the pan take it out.
Squeeze the topping into lumps with your fingers as you add it to the cake. Get all of the cake covered with the crumb topping and put it back into the oven. After ten minutes check the cake by inserting a toothpick or a knife into the center of the cake. When it comes out clean take your Crumb cake out of the oven and place it somewhere where the bottom of the pan is not right on a flat surface so that it will cool evenly. The top of the stove will work for that if you don't have anything else going on up there. This is what I do.
After about a half hour you can add the powdered sugar. Using a sifter or just your hand sprinkle the powdered sugar all over the crumb cake.