Preheat oven to 350 degrees. Spray a 9x13 dish with cooking spray. Set aside.
Measure 2 teaspoons of the dry cake mix and place in a small bowl. Set aside.
Place the remaining cake mix, sour cream, vegetable oil, water, and eggs in a large mixing bowl. Beat with an electric mixer on low speed until incorporated. Increase the speed to medium and beat until the mixture lightens and is smooth, about 2 minutes, scraping down the sides of the bowl. Pour batter into the prepared pan.
For the filling, drizzle the honey across the top of the batter. In a small bowl, combine the brown sugar, cinnamon, and pecans. Sprinkle the mixture evenly on top of the honey and swirl into the cake batter with a butter knife.
Place the blueberries in the bowl with the reserved cake mix and toss to coat. Sprinkle the blueberries on top of the batter and place cake in the oven.
Bake until the top springs back when lightly pressed with a finger, about 40-45 minutes. Remove the pan from the oven and let the cake cool while you prepare the glaze. (I did not glaze the cake myself.)
For the glaze, place the powdered sugar in a small bowl and whisk in the milk and vanilla until smooth. Spoon the glaze over the warm cake and serve.