Dice onion and set aside. Dice ham into small pieces and set aside. Cut cauliflower florets off, discard the stem, and chop florets onto small pieces. Set it aside as well.
Preheat a medium pot over medium heat with some oil. Add diced onion and saute until transparent. Add ham and cook for a few minutes. Add pressed garlic, mix, and cook until fragrant.
Add prepared cauliflower, mix well and cook for a few minutes.
Sprinkle flour over veggies and ham and mix well.
Pour in chicken stock, while slowly stirring. Enough chicken stock to just covers the cauliflower mixture.
Add bay leaf, salt, pepper, and sage. Stir and cover with a lid, leaving a crack for steam to escape. Cook for 20-25 minutes.
Stir in heavy whipping cream and grated white cheddar cheese. Cook for a few more minutes and serve.
**To make this soup gluten-free, substitute flour with either gluten-free flour or 1 tbsp of corn starch.**