Combine flour, sugar, baking soda, baking powder, salt, and lemon peel in a large bowl.

In a small bowl, stir together the egg, sour cream and canola oil.

Mix the wet ingredients until the dry ingredients until well combined. Gently stir in the blueberries.

Coat a 2 quart souffle pan with cooking spray. Add the batter. Lower into the slow cooker. Cover with a piece of foil and wrap tightly so no water gets into batter.

Pour 2 cups of hot water into the slow cooker.

Set the slow cooker to high and cook for 3 to 3 1/2 hours.

When baked, turn cake upside down onto a wire rack. Allow to cool.

Dust with powdered sugar if desired before serving.