Preheat oven to 350℉. In a large skillet, heat the butter over low heat. Add garlic and cook for 2-3 minutes. Remove from heat and set aside. I highly recommend using a garlic press with this amount of garlic otherwise ok to use the jarred minced garlic but know the garlic flavor might not be the same.
In a large pot, bring the vegetable broth and water to a boil. Add cauliflower florets and boil for 8 minutes or until a fork can easily pierce cauliflower.
In a large food processor or high-powered blender, use a slotted spoon to transfer the cauliflower florets, plus add 1 cup of broth/water mix, sautéed garlic and butter, salt, pepper, and milk. Process until consistency is smooth. If consistency is too thick for your liking you can add a little more milk.
Spoon sauce over stuffed pasta shells.
Bake at 350℉ for 30 minutes.
Serve.