Preheat oven to 350°F. Spray an 8x8 inch baking dish with cooking spray.
Place the cream-style corn, cream cheese, flour, onion powder, and salt in a large saucepan. Heat over low heat, stirring occasionally, until the cream cheese is melted.
Stir in the whole kernel corn and Swiss cheese. Pour the mixture into the prepared pan.
In a small bowl, mix together the breadcrumbs and butter. Sprinkle over the corn casserole.
Bake for 25–30 minutes, or until the mixture is light brown on top and bubbly on the edges.
Notes
Swap out the Swiss cheese for your favorite shredded cheese, such as cheddar, Gruyere, colby jack, or pepper jack. I like using salted butter for the topping. If you use unsalted, add a pinch of salt.Store any leftovers in the refrigerator for 3–4 days. Reheat in the microwave for 1–2 minutes or the oven at 350°F for 10–12 minutes, or until warm. The oven method is best for retaining some crispiness in the breadcrumbs. Make it ahead: prepare the casserole as directed, but do not prepare the breadcrumb topping. Place the casserole in the refrigerator, tightly sealed with plastic wrap, for up to 2 days before baking. Make the breadcrumb mixture and top the casserole right before baking to ensure the topping stays crisp.