SERVES: makes one 9 x 13-inch cake
For the streusel:
• 1/2 cup light brown sugar
• 1/2 cup dark brown sugar
• 1 cup all-purpose flour
• 4-ounces cold butter, cubed
• 4 tsp ground cinnamon
For the cake:
• 1 stick plus 2 Tbs unsalted butter, room temperature (10 Tbs total)
• 1 cup white sugar
• 4 large eggs
• 1 cup sour cream
• 2 tsp vanilla
• 2 cups all-purpose flour
• 1 Tbs baking powder
• 1 tsp baking soda
• 1 tsp salt
• 1 1/2 cups frozen blueberries (or fresh in season)
1. Preheat the oven to 350 degrees and also butter one 9 x 13-inch baking dish.
2. Use a mixing bowl to combine 1/2 cup each of light brown sugar and dark brown sugar with 1 cup all-purpose flour and 4-ounces of cold, cubed butter, and use your fingers to completely incorporate the butter. Then fold in 4 tsp ground cinnamon and set that aside.
3. Next, for the cake, use an electric mixer to cream 1 stick plus 2 Tbs room temperature butter with 1 cup white sugar. Then add 4 large eggs, and then 1 cup sour cream, and 2 tsp vanilla, and turn the machine off.
4. For the dry ingredients, use another mixing bowl to combine 2 cups all-purpose flour with 1 Tbs baking powder, 1 tsp baking soda and 1 tsp salt, and then turn the machine onto low and slowly add the dry ingredients to make the batter.
5. Next, spread half of the batter into the buttered baking dish and then top that with 2/3 of the streusel. Sprinkle on 1 1/2 cups frozen blueberries, carefully top that with the rest of the batter. Sprinkle on the rest of the streusel and place the baking dish onto the center rack of the preheated oven.
6. That will take just about 45 minutes to bake. Use a toothpick to check it for doneness.
HINTS: It's best to use a little less than half the batter for the first layer. Adding the second layer of batter can be a little bit of a challenge because it wants to stick to the blueberries and streusel. Don't worry if the second layer doesn't completely cover the dish, just add the final topping of streusel and bake, it will bake just fine.