Creamy Ham Potato and Corn Chowder

Ingredients

2 cups cooked ham , diced into small cubes (I used left over ham roast, ham steak works too)
6 slices bacon , cooked and crumbled
5 1/2 Tbsp butter , divided
1 medium yellow onion , diced (1 1/2 cups)
2 carrots , peeled and diced (3/4 cup)
2 celery stalks , diced (3/4 cup)
2 (14.5 oz) cans low-sodium chicken broth
5 medium red potatoes (1 3/4 lb), diced into 3/4-inch cubes
3/4 tsp dried oregano
1/2 tsp dried thyme
1 bay leaf
Salt and freshly ground black pepper , to taste
2 cups fresh corn (or frozen)
1/3 cup all-purpose flour
3 cups milk
1/2 cup sour cream or heavy cream (I've tried and like both versions)
Chopped green onions or chives, for serving

In a large pot, melt 1 1/2 Tbsp butter over medium heat. Add onion, carrot, and celery and saute until tender, about 4 minutes. Add chicken broth, potatoes, oregano, thyme, and bay leaf and season with salt and pepper to taste*.
Bring mixture to a boil over medium-high heat, then reduce heat to medium, cover with lid and allow to cook, stirring occasionally until potatoes are nearly tender, about 15 minutes.
Add in ham and corn and cook until potatoes are tender, about 5 minutes longer.
Meanwhile, in a medium saucepan, melt remaining 4 Tbsp butter over medium heat. Add flour and cook mixture, stirring constantly, 1 1/2 minutes.
While whisking, slowly add in milk, and whisk vigorously to smooth lumps, season with salt and pepper to taste. Bring mixture to a boil and allow to thicken, whisking constantly.
Remove from heat, stir in sour cream or cream. Pour and stir milk mixture into soup mixture (once potatoes are tender). Serve warm topped with bacon and chives.