Preheat oven to 400F.
Over medium-high heat, add butter to a medium skillet. Saute onion, salt, and pepper until onion slightly transparent, then add the roasted red pepper or sundried tomato (whichever you decide to use) and allow to saute another 2-3 minutes.
In a medium bowl, add the two cans of creamed corn, the drained corn kernels, 1 sleeve of the crushed crackers, the eggs, and the contents of the skillet. Mix thoroughly.
Spray a medium baking dish with cooking spray, and empty the contents of the bowl into the dish. Top with the remaining crushed crackers. Bake 1 1/2 hours, until no longer jiggly in the middle.