This crumb coffeecake is absolutely delicious, plus it is so quick and easy! I feel like I say that about all my recipes, but do keep in mind that that is a quality I look for when picking out recipes, so that's most likely why. I'm being completely honest when I say it though. It took maybe 20 minutes tops for this huge, delicious coffeecake to get in the oven for our Mother's Day brunch. You may feel while making it (like I did), that you have WAY too much crumb topping, but it's not as crazy as you think and it's totally worth it in the end, so just believe me when I say: USE IT ALL!
Make the coffeecake: Preheat the oven to 350 degrees. Grease a 9 x 13-inch pan with cooking spray.
In a large mixing bowl, cream the butter and sugar until light and fluffy. Add the eggs one at a time, and beat between additions. Scrape down the mixing bowl, then beat in the vanilla and sour cream. In a medium sized bowl, whisk the flour, baking soda, salt, and baking powder together. Add to the butter/sour cream mixture, mixing until evenly combined.
Make the crumb topping: In a large bowl, whisk together the flour, sugar, salt, and cinnamon. Melt the butter and add the vanilla to it. Now using a rubber spatula (take out the whisk, it will get crumbly!), pour the butter into the flour mixture and mix until no flour is showing and you have a uniformly moistened crumb mixture.
Crumble the crumb mixture over the top until the batter is completely covered. Bake for 30 to 35 minutes, or until a tester inserted in the center comes out clean.