In a large saucepan or Dutch oven, combine the diced potatoes and vegetable broth.
Bring the mixture to a boil over medium-high heat, then reduce the heat to maintain a simmer.
Cover and cook for 4 minutes until the potatoes begin to soften.
Pour in the milk and return the soup just to a simmer, watching carefully to ensure it doesn't boil over. Small bubbles should form around the edges.
While the soup heats, combine the shredded Swiss cheese, all-purpose flour, and Italian seasoning in a medium bowl.
Toss gently with your fingers or a fork until the cheese is evenly coated. This step is key to preventing the cheese from clumping in the hot liquid.
Gradually sprinkle the cheese mixture into the simmering soup, a little at a time, stirring constantly and smoothly until all the cheese has melted.
Continue to cook and stir over medium heat for 2-3 minutes, until the soup has thickened and is bubbly.
Stir in the rinsed and drained navy beans.
Cook for 1 more minute, just to heat the beans through.
Season to taste with salt and pepper, then serve immediately.
Garnish with fresh chives, chopped parsley, or a sprinkle of smoked paprika for a pop of color and an extra layer of flavor.
