In a large saucepan, melt butter.
Stir in flour and garlic powder. Add milk, all at once.
Cook over medium heat, stirring constantly, until mixture is thickened and bubbly.
Stir in Colby-Jack and cream cheese. Cook, stirring over low heat until cheese melts.
Stir in corn and ham (or bacon).
Pour into a 2-Quart casserole pan. Bake at 350 degrees for 45 minutes or until heated through.
