In a large bowl, beat the cake mix, eggs, vegetable oil, sour cream and vanilla extract until well blended.
Gently fold in blueberries and set aside.
In another bowl combine the brown sugar, cinnamon and candied pecans.
Spray the loaf pans with non-stick spray and fill 1/3 full of batter and sprinkle with a small amount of the brown sugar mixture.
Top with additional cake mix until pan is 3/4 and sprinkle with additional brown sugar topping.
Place rack into any CanCooker and add 2 cups water.
Place two cakes on rack, close lid and on a medium heat source bring to a steam.
Steam cakes for 30 minutes or until toothpick inserted in center comes out clean.
With tongs carefully remove the cakes from the CanCooker and place on a cooling rack.
Repeat with remaining two loaf pans.
After cooling invert loaf pans onto a serving plate.
Dust with powdered sugar if desired.