Preparation Steps

• Preheat oven to 350°F (175°C). Grease and flour a 9x13 inch baking pan.
• In a large 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 vanilla extract.
• In a separate bowl, whisk together the flour, baking powder, baking soda, and salt. Gradually add the dry ingredients to the wet ingredients, alternating with the sour cream, beginning and ending with the dry ingredients. Mix until just combined.
• In a small bowl, combine the flour, brown sugar, butter, and cinnamon for the streusel topping. Cut in the cold butter using a pastry blender or your fingers until the mixture resembles coarse crumbs.
• Pour the batter into the prepared pan and spread evenly. Sprinkle the streusel topping over the batter.
• Bake for 35-40 minutes, or until a wooden skewer inserted into the center comes out clean. Let cool in the pan before cutting into squares and serving.