This is a wonderful recipe. Comfort food at its finest! A beautiful blend of ham, potatoes, cheese, corn... what's not to love! Sometimes I add about 1/4 c. of shredded cheddar to the white sauce at the very end. A favorite in our family from the very youngest to the oldest. Recipe from my buddy and partner in cooking adventures, Russ.
In a large bowl, combine first 4 ingredients; set aside. Saute onion in butter for 2 minutes. Then, stir in flour until blended. Cook, stirring for 1 minute. Gradually whisk in milk, and pepper.
Bring to a low simmer and stir for 2 minutes. I occasionally add 1/4 c. shredded cheddar at this point, too. Remove from heat, pour over the ham mixture and stir to combine. Taste test for salt. Add 1/8- 1/4 tsp. depending on the saltiness of your ham.
Transfer to a greased 11x7x2 baking dish.
Cover and bake at 350 degrees for 25 minutes. Uncover and sprinkle with cheese. Bake 5-10 minutes longer until cheese is melted.