Place cauliflower and water in the inner pot, secure lid for pressure cooking. Select PRESSURE COOK, HIGH, set time for 1 minute, then press START. Quick Release the pressure then press CANCEL. Strain the cauliflower and set aside.
Select SAUTE and press START. Add the olive oil and butter, allowing the butter to melt. Add onion and garlic and sauté for 1-2 minutes or until translucent and fragrant, stirring frequently.
Add the oregano, sauté until fragrant. Add flour and stir until it disappears.
Add milk, and cream. Stir until the sauce is thick.
Add in the cauliflower, and one cup of cheese, mix it in. Press CANCEL.
Sprinkle the rest of the cheese on top and cover the pot with the Air Frying lid.
Select BROIL, set the time to 7 minutes and press START, or until cheese is melted golden in color.