In a large kettle, combine the potatoes, celery, onion, garlic, pepper, salt, and chicken broth.
Bring to a boil and then low to a simmer for 15-20 minutes, until potatoes are soft. Remove from heat.
Carefully pour vegetables and stock into a heat safe bowl and set aside.
Keeping the kettle heated over medium heat, add the butter and stir until fully melted.
Stir in the flour and continue to stir/whisk until a golden brown color is created, about 3 minutes.
Slowly stir in the milk, adding 1/3-1/2 cup at a time. Heat and stir until it thickens.
Once all milk has been incorporated, slowly reincorporate the chicken stock and vegetables.
Add in ham and continue to cook over a medium heat until the ham is heated through.
Taste test, and add additional salt and pepper to taste.