I must confess, I love streusel and crumb toppings far more than the average person. In fact, I created this entire recipe just so I could eat the crumb topping. Most people plan outfits around a new pair of shoes or fun accessory. I, however, plan desserts around one component. And when it comes to breakfast, you simply can’t beat a good streusel topping (at least that’s my opinion). So, I created this coffee cake to highlight an incredibly decadent crumble topping. A slightly tart lemon blueberry filling helps balance the sweet crumble topping. The cake component of this coffee cake is light and airy, which contrasts the richness of the buttery, walnut filled topping in a wonderfully tasty way. While you may be tempted to polish off this coffee cake all by yourself (I have been known to do this 🙂 ), this is a fantastic treat to share! This will definitely be on the menu for my family’s Easter brunch!
Tasty Tip: Whenever you zest a lemon, you only want to use the yellow part of the rind. The white part of the lemon (the pith) is quite bitter!
In this recipe, I ask you to divide the dry ingredients in half at one point. It does not need to be exact. I simply smooth the top, draw a line down the center, and then spoon one half into a separate bowl. Don’t you love it when things don’t have to be perfect!
Here’s what the crumble topping will look like after you stir in the walnuts. I typically “taste test” a bit of the topping at this point…purely for the sake of quality control 🙂
The coffee cake batter will be light and airy once you have combined all the ingredients. Stop stirring at this point (even if some flour particles are still visible). This will prevent the coffee cake from becoming tough.
To assemble the coffee cake, spread the batter into the bottom of the cake pan. Pour the lemon blueberry filling on top, and then sprinkle the crumb topping over the blueberries. The coffee cake will rise significantly in the oven, so place a sheet of foil under the cake pan to catch any overflow. The crumble topping will be golden brown when the coffee cake is done.
- ¼ cup granulated sugar
- Juice of one lemon (about ¼ cup)*
- 1 Tablespoon cornstarch
- ½ cup blueberries
- 1 ¼ cup light brown sugar
- 2 cups all purpose flour
- ¼ cup cornstarch
- 1 teaspoon salt
- 1 teaspoon cinnamon
- ¼ teaspoon nutmeg (optional)
- 8 Tablespoons cold unsalted butter, cut into small pieces
- 1/3 cup walnuts, chopped into small pieces
- 2 teaspoons baking powder
- 1 teaspoon baking soda
- ¾ cup sour cream
- ½ cup vegetable oil
- 1 egg
- 1 teaspoon vanilla extract
- Zest of one lemon
- *Note: Zest the lemon before you cut it in half to squeeze out the lemon juice. You will need the zest for the coffee cake batter.
- In a small saucepan over medium heat, combine the sugar, lemon juice, and cornstarch. Stir constantly until the sugar has dissolved and there is visible steam, about 3-5 minutes. Turn off the stove. Stir in the blueberries.
- Preheat the oven to 325 degrees Fahrenheit. Grease a 9-inch cake pan.
- In a large bowl, thoroughly combine the brown sugar, flour, cornstarch, salt, cinnamon, and nutmeg. Transfer half of this dry ingredient mixture into a medium bowl. To this medium bowl, add the cold butter. Using a fork, pastry cutter, or your hands, work the butter into the dry ingredients until pea-sized clumps begin to form. Stir in the walnuts.
- To the large bowl that contains half of the dry ingredient mixture, stir in the baking powder and baking soda. In separate bowl, whisk together the sour cream, vegetable oil, egg, vanilla extract, and lemon zest. Pour these wet ingredients into the large bowl and stir the batter until the wet and dry ingredients are incorporated. The batter should be light and spongy. Do not overstir. It’s okay if there are still some visible flour particles.
- Spread the coffee cake batter into the prepared cake pan. Spoon the lemon blueberry filling evenly over the batter. Sprinkle the crumble topping over the blueberry filling. Bake for 45 minutes. A toothpick inserted in the center of the coffee cake should come out clean or with a few crumbs and bits of blueberry. **Note: The batter will rise quite a bit in the oven, so place a sheet of foil beneath the cake pan to catch any overflow. **