1-First Step: Make the streusel topping Start by combining the light brown sugar, flour, cinnamon, and salt in a small bowl. Mix with your fingers until no lumps remain. Then rub in the cold butter chunks until the mixture turns crumbly and looks like damp sand with some pea-sized pieces. This step matters because cold butter gives the streusel its texture. Once it is ready, place the bowl in the refrigerator while you make the batter. Chilling the topping keeps it from melting too fast in the oven, so it bakes into a crisp layer instead of disappearing into the cake.

2-Second Step: Get the pan and oven ready Preheat the oven to 375°F (190°C) and move the rack to the middle position. Grease a 9-inch square pan well so the cake releases easily after baking. If you like, you can line the pan with parchment for even easier lifting, but that is optional. Getting the oven fully heated before the batter goes in helps the cake rise properly. A hot oven also gives the streusel a golden top while the inside stays moist and tender. This is a small step, but it helps the Blueberry Coffee Cake bake evenly from edge to center.

3-Third Step: Mix the dry ingredients In a medium bowl, whisk together the flour, baking powder, and salt. Set this bowl aside for later. Whisking now spreads the baking powder evenly through the flour, which helps the cake rise without dense pockets. If you are using a gluten-free flour blend, whisk it the same way and keep the rest of the method unchanged. This dry mixture is the base of the batter, so try not to skip the whisking step.

4-Fourth Step: Cream the butter and sugar In a large bowl, beat the softened butter and granulated sugar until creamy, about 2 minutes. The mixture should look lighter in color and feel fluffy. This step adds air to the batter, which helps the cake bake with a soft crumb. Add the eggs one at a time, mixing well after each one and scraping down the bowl as needed. Then beat in the vanilla extract and lemon zest. The lemon zest adds a fresh note that keeps the cake from tasting too heavy.

5-Fifth Step: Add the flour mixture and milk With the mixer on low speed, add the flour mixture and milk alternately. Start with a little flour, then a little milk, and repeat until both are used. Mix only until combined. Overmixing can make the cake tough, so stop as soon as the batter looks smooth. If you are making a healthier version, this is also the point where you can use part whole wheat flour. Just keep the swap modest so the texture stays soft.

6-Sixth Step: Fold in the blueberries Gently fold in the blueberries with a spatula. Use slow, careful strokes so you do not break the fruit. If you are using frozen blueberries, do not thaw them first. Adding them straight from the freezer helps prevent color bleeding and keeps the batter from turning gray-purple. If you want to keep the berries from sinking, you can toss them lightly with a spoonful of flour before folding them in. That little trick helps distribute them more evenly through the cake.

7-Seventh Step: Assemble and bake Spread the batter in the prepared pan and smooth the top. Sprinkle the chilled streusel evenly over the batter. Try to cover the surface from edge to edge so every slice gets a bit of crunchy topping. Bake for 40 to 45 minutes, or until the edges are golden and a tester inserted into the center comes out clean. If you use a loaf pan or a different pan size, the bake time may change, so start checking early. Some ovens run hot, so keep an eye on the top and tent with foil if it browns too quickly.

8-Eighth Step: Cool and serve Let the cake cool in the pan on a rack for 20 minutes. That short rest helps the crumb set, making slices easier to cut. After that, you can serve it warm, room temperature, or slightly cooled. This Blueberry Coffee Cake is best the same day it is baked, when the streusel is still crisp and the berries taste bright. If you want a simple morning treat, serve it with coffee, tea, or cold milk. For a cozy brunch spread, pair it with yogurt, fresh fruit, or eggs. For another simple make-ahead breakfast idea, you may also enjoy our homemade brunch recipes.