Preheat oven to 350 degrees.
Saute diced onion in a small skillet with 1 tbsp canola oil until softened, 5 mins.
Thaw the frozen creamed corn and add to a large bowl along with the whole kernel corn, pepper, onion, sour cream, half and half, sugar, salt and pepper. Also add 13 crushed crackers and fold together
Pour the corn mix into a greased 3 quart casserole dish.
Melt the 2 tbsps. butter in a skillet, then mix in 10 crushed crackers and stir to coat the crumbs. Remove the crumbs to a small bowl and sprinkle the crumbs evenly on the corn.
Bake the casserole for 40 to 50 minutes, until the crumbs are starting to brown and there's bubbling around the edges.
Remove from the oven and let rest for 10 minutes before serving.