Preheat oven to 425°. Place cauliflower on a large baking sheet. (line with foil for easy cleanup) Drizzle with olive oil and season with salt and pepper. Toss to combine and crumble 2 thyme sprigs on top.
Bake 20 minutes, until cauliflower is golden and tender.
In a large pan, over medium heat, cook bacon until crispy. Remove cooked bacon slices and drain on a paper towel-lined plate and chop bacon into small pieces.
Add a bit of bacon fat from the pan to the Instant Pot liner and press Sauté button.
Add onion to bacon fat and cook until tender, about 5 minutes. Stir in garlic and cook until fragrant, another minute, and then pour in the wine. Cook until wine has mostly reduced down, about 2-3 minutes.
Add roasted cauliflower to the Instant Pot and pour in the chicken broth. Add bay leaf and remaining thyme sprigs.
Set the Instant Pot to Manual high pressure for 3 minutes. Use the natural release method after the 3 minutes are up and chop the cauliflower with a wooden spoon.
Using an immersion blender, purée until smooth.
Season to taste with salt and pepper, and then stir in heavy cream.
Serve warm with cheddar, chopped bacon, and green onions.
