Follow package instructions to prepare muffin mix.
Fold in frozen or fresh blueberries to batter.
Into prepared spring form pan, pour in batter and top with topping mixture, patting gently onto top of batter until evenly distributed.
Place into the preheated 375 degree oven for 5 minutes, then reduce heat to 350 degrees for the remaining 35-40 minutes
Take out of the oven when a toothpick inserted in the middle comes out clean.
Place onto a wire cooling rack, and after 10 minutes gently release sides with a knife, then release the spring latch to separate from pan. To remove cake from the bottom of the pan, use a spatula around all edges until it comes loosened to transfer to a serving plate.