Place the diced potatoes, carrots, and garlic into a large stockpot. Pour in the water, making sure it barely covers the vegetables. Add the bouillon base, parsley, and 1 teaspoon of salt.

Bring the pot to a boil over high heat. Reduce to a medium simmer, vent the lid, and cook for 20 minutes until the vegetables are fork tender.

Remove from heat and mash the soup with a potato masher until it reaches your desired texture.

In a separate pot, melt the butter over medium heat. Whisk in the flour, 1/2 teaspoon salt, and pepper to form a paste. Cook for 2 minutes.

Slowly whisk in the milk, one cup at a time, to prevent any flour lumps. Let it boil for 1 minute over medium heat, stirring constantly, until thickened.

Pour the creamy white sauce into the mashed potato pot and stir well before serving.