Preparation Steps

• Preheat oven to 350°F (175°C). Butter a 9x13 inch baking dish.
• In a medium bowl, whisk together the flour, baking powder, baking soda, and salt for the cake. Set aside.
• In a large mixing bowl, cream together the softened butter and granulated sugar until light and fluffy.
• Beat in the eggs one at a time, then stir in the sour cream and vanilla extract.
• Gradually add the dry ingredients to the wet ingredients, mixing until just combined. Do not overmix.
• Pour the batter into the prepared baking dish and spread evenly.
• In a separate medium bowl, combine all ingredients for the crumb topping: flour, light brown sugar, granulated sugar, salt, and cinnamon. Pour in the melted butter and mix with a fork until coarse crumbs form.
• Sprinkle the crumb topping evenly over the cake batter.
• Bake for 50-55 minutes, or until a toothpick inserted into the center of the cake comes out clean.
• Let the cake cool in the pan for at least 30 minutes before slicing and serving.