Combine all ingredients except cheese and green onions in a blender. Blend just to combine. Refrigerate for 30 minutes. Preheat oven to 200F (93C).
Heat bubble waffle iron (or regular waffle iron) according to the manufacturers’ directions. Once hot, brush lightly with canola oil. Pour ¼ cup (60ml) batter into the centre of the mold, allowing it to run to within 1-1/2 inches (3cm) of edge of pan.
Scatter approximately 1/6 of the cheese and onions over the top, cover with another ¼ cup (60ml) of batter, close the lid of the iron and if using a bubble waffle pan, flip the pan over immediately. Allow the waffle to cook for about 2 minute per side or 4 to 5 minutes total, turning iron halfway. Place finished waffle on rimmed baking sheet and place in warm oven. Repeat with remaining batter. Serve warm.