Preheat the oven to 350°F (180°C). Spray a 9x13-inch pan with nonstick cooking spray and set aside.
To make the topping: Add the flour, brown sugar, and cinnamon to a large mixing bowl and whisk until well combined. Add the cubed butter and cut it into the mixture with a pastry cutter or a fork until the mixture starts to come together and is crumbly. Cover and transfer to the refrigerator while you prepare the cake.
To make the blueberry cake: In a large mixing bowl, whisk together the flour, baking powder, ground cinnamon, and salt until well combined. Set aside.
In the bowl of a stand mixer fitted with the paddle attachment or in a large mixing bowl using a handheld mixer, beat the butter and granulated sugar together until light and fluffy (about 3 to 4 minutes).
Mix in the eggs, one at a time, until fully incorporated, then mix in the sour cream and vanilla extract, stopping to scrape down the sides of the bowl as needed.
Mix in the dry ingredients until just combined, the batter will be very thick. Gently fold in the blueberries until fully incorporated.
Scoop the batter into the prepared pan and smooth it out. Remove the topping from the refrigerator and sprinkle it on top of the cake.
Bake for 30 to 35 minutes or until a toothpick inserted into the center of the cake comes out clean.
Remove the cake from the oven and cool on a wire rack in the pan for at least 45 minutes to 1 hour, then slice and enjoy!