Classic Crumb Cake

Instructions

1. Preheat the oven to 350 degrees F. Generously butter a 13x9 inch baking pan (I used a metal pan, but a pyrex would work, too).
2. In a medium bowl, whisk together the flour, baking soda, baking powder and salt. Set aside.
3. In a large bowl (or the bowl of a stand mixer), beat the butter and sugar until light and fluffy, about 4 minutes (scrape sides of bowl during mixing to incorporate all of the ingredients). Beat in the eggs one at a time. Mix in the vanilla. Add the flour mixture, then the sour cream. Beat just until combined.
4. Scrape the batter into the prepared pan, and use a rubber spatula to spread it into an even layer.
5. In a medium bowl, whisk to combine the flour, sugar, cinnamon and salt; cut in the butter using a pastry blender, until large, moist clumps form. (I used a food processor to combine the butter and the other ingredients, pulsing until crumbs formed. The crumbs were smaller than the large, moist clumps as described by Martha, but they worked perfectly fine in the recipe anyway).
6. Sprinkle the crumb topping evenly onto the batter. Bake until cake is golden brown and a toothpick inserted into the center comes out clean, 40 to 50 minutes. The center of the cake should feel slightly firm to the touch and not soft and soggy. Transfer to a wire rack to cool. Slice and eat!