Melt the butter in a large skillet over medium heat. Add the flour and cook, stirring, for 1 minute. While whisking, slowly add the milk. Reduce the heat to low and simmer, whisking occasionally, for 5 to 10 minutes, or until the milk is thick enough to coat the back of a spoon.

Stir in the corn, garlic, salt, and several grinds of pepper. Cook, stirring occasionally, for 17 to 20 minutes, or until thickened. Add the Parmesan and stir until melted. If the mixture has thickened too much, add more milk, 1 tablespoon at a time, as needed to reach your desired consistency.

Season to taste and serve.