Heat oil in a pan and add the finely diced onions.
Saute until it gets a glassy / translucent look.
Add the crushed garlic and saute on medium to high heat until the garlic is fragrant for about 3-5 minutes.
Add the optional sliced mushrooms and saute until the mushrooms are reduced in size and get a brownish color.
Until we wait for the onion and the mushrooms, get the cauliflower ready in a food processor or with a manual shredder. Or with our trusty knife.
Mix the cauliflower rice with the onion and optional mushrooms.
Add stock or simply a bit of water into the pan, mix everything together and cook it under lid until the cauliflower gets a desired texture for about 3-10 minutes.
Mix in the grated hard cheese.
Wait a bit until it melts and cauliflower risotto is ready to be served.