Preheat oven to 350ºF and spray large 10.5 x 15” jelly roll pan or rimmed cookie sheet (I used a half bun pan) with nonstick spray.
In a large bowl, cream together canola oil, butter and sugar. Add eggs and vanilla and beat well. Add the flours and baking soda and stir just until the batter comes together.
Spread 2/3 of the batter in the bottom of the pan. Sprinkle with berries or sliced fruit, then drop the remaining dough in spoonfuls over the fruit - it will spread as it bakes, and you don't need to cover it all.
Bake for 30-40 minutes, until golden and springy to the touch.