Preheat oven to 400°F (200°C).

In a large pot, heat olive oil over medium heat. Add onion and cook until softened, about 5 minutes. Add garlic and thyme and cook for 1 minute more.

Add potatoes and milk to the pot. Bring to a boil, then reduce heat and simmer for 20-25 minutes, or until potatoes are tender.

Place cauliflower mixture and milk in a blender or food processor. Blend until smooth.

Add half of potato mixture to blender and pulse 5 to 6 times or until coarsely chopped. Repeat with remaining potato mixture.

Place cauliflower-potato mixture in Dutch oven over medium heat. Stir in remaining salt, pepper, green onions, and fromage blanc. Stir until fromage blanc melts.

Top evenly with remaining green onions, cheese, and bacon.