First Step: Preheat and Prepare Your Baking Pan
Begin by preheating your oven to 350°F (175°C). Choose a 9-inch springform pan or a 9×9-inch square baking pan for best results. Grease the pan thoroughly with butter or non-stick spray, then line the bottom with parchment paper to prevent sticking and allow easy cake removal.

Second Step: Make the Cream Cheese Layer
In a medium bowl, blend 8 oz. of softened cream cheese with ¼ cup (50 g) granulated sugar and ½ teaspoon pure vanilla extract until smooth and creamy. Mix in 1 egg white (or a whole egg for a richer variation) until fully incorporated. Set this luscious cream cheese mixture aside for layering.

Third Step: Combine Dry Ingredients
In a separate bowl, sift together 1 ½ cups (190 g) all-purpose flour, ½ teaspoon baking powder, ½ teaspoon baking soda, and ¼ teaspoon salt to ensure even rising and a light crumb.

Fourth Step: Cream Butter and Sugar
Cream 5.5 tablespoons (78 g) softened unsalted butter with ½ cup (100 g) granulated sugar until light and fluffy, approximately 3-4 minutes with an electric mixer on medium speed. This step incorporates air, making the cake tender.

Fifth Step: Incorporate Eggs and Vanilla
Beat in 1 whole egg plus 1 egg yolk (or 2 large eggs) and 1 teaspoon pure vanilla extract until fully mixed and smooth. The eggs add richness and stability to the batter.

Sixth Step: Alternate Adding Dry Ingredients and Sour Cream
Add the sifted dry ingredients and ¾ cup (180 ml) sour cream alternately to the wet ingredients, beginning and ending with the dry mix. Mix gently to just combine overmixing can lead to a dense cake.

Seventh Step: Fold in Fresh Blueberries
Carefully fold in about 1 cup (150 g) of fresh blueberries to distribute them evenly throughout the batter without breaking them, preserving the beautiful color and flavor.

Eighth Step: Layer Batter and Cream Cheese
Pour half of the batter into your prepared pan, spreading it evenly. Sprinkle some fresh blueberries on top, then spread the cream cheese layer over the batter and blueberries. Add the remaining blueberries evenly over the cream cheese layer. Finally, cover with the remaining cake batter.

Ninth Step: Prepare and Add the Streusel Topping
To make the streusel, mix ⅓ to ½ cup (67-100 g) granulated or light brown sugar with ½ to ¾ cup (63-95 g) all-purpose flour. Cut in 3 tablespoons (42 g) chilled diced unsalted butter using fingers or a pastry cutter until pea-sized crumbs form. Optionally add ½ teaspoon ground cinnamon or chopped nuts. Sprinkle this crumbly topping evenly over the cake.

Tenth Step: Bake the Coffee Cake
Bake for 40-70 minutes depending on your pan size and batter thickness. Begin checking at 40 minutes by inserting a toothpick into the center; it should come out with a few moist crumbs but no wet batter. If the streusel browns too quickly, loosely cover with foil to prevent over-browning.

Final Step: Cool and Serve
Allow the cake to cool for 10-15 minutes before releasing it from the pan. Transfer to a wire rack to cool completely. Optionally, dust with confectioners’ sugar or drizzle with a lemon glaze made from powdered sugar and fresh lemon juice. Enjoy warm or at room temperature for a moist, flavorful blueberry cream cheese coffee cake experience!