Preheat the oven to 350 degrees F. Line the bottom and two opposite sides of an 8-inch square baking pan with parchment paper, leaving enough parchment on the two opposite ends to create handles for lifting the dessert bars out of the pan.
Add all-purpose flour, baking soda, baking powder, kosher salt to small mixing bowl. Whisk to combine. Set aside.
Add whole milk, sour cream, fresh lemon juice, fresh lemon zest and vanilla bean paste to small bowl. Whisk to combine. Set aside.
Add unsalted butter to stand mixer. Beat on medium for 3 minutes. Add granulated sugar and light brown sugar and beat on medium for 2 minutes.
Add eggs one at a time. Beat on low after each addition until fully incorporated, about 15 seconds.
Add the reserved milk mixture to the sugar mixture. Beat on low until fully incorporated.
Remove the bowl from the stand mixer. Add half the flour mixture and fold in using a large spatula. Add the remaining flour mixture and fold in until no flour streaks are visible.
Transfer half the coffee cake batter to the prepared baking pan and level with a small offset spatula.
Sprinkle half the reserved crumble evenly over the cake batter. Top the pecan crumble with half the fresh blueberries.
Dollop the remaining batter over the blueberries and spread evenly with small offset spatula.
Sprinkle remaining pecan crumble evenly over cake batter. Top with remaining fresh blueberries.
Bake 50 minutes, or until a toothpick inserted in the center of the cake comes out clean.
Cool the blueberry coffee cake on a wire rack to room temperature. Remove the cake from the baking pan by tilting the pan slightly and using one side of the parchment paper as a handle to lift and slide the cake out.
Cut cake into individual servings. Store cake in an airtight container in the refrigerator for several days.