Preheat: Set oven to 425°F / 220°C and line a rimmed baking sheet.
Prep cauliflower: Toss 1,000 g florets with 2 tbsp olive oil, ½ tsp salt and ¼ tsp pepper. Spread on sheet in a single layer. Roast 20–25 minutes, turning once, until golden and tender.
Heat sauce: In a small saucepan, warm 240 g heavy cream until steaming. Whisk in 120 g softened cream cheese until smooth. Remove from heat.
Temper eggs: Whisk 2 eggs lightly in a small bowl. To avoid scrambling, stir a spoonful of hot cream into the eggs, then whisk the egg mixture into the saucepan. Add 1 tsp Dijon, garlic, nutmeg (if using) and 150 g shredded cheddar (reserve 50 g). Season to taste.
Assemble: Transfer roasted cauliflower (and optional chicken, turkey or beef bacon / chicken) to a 9x9-inch baking dish. Pour sauce evenly over cauliflower. Sprinkle reserved cheddar.
Make topping: Stir 60 g almond flour + 40 g Parmesan + 30 g melted butter until crumbly. Sprinkle evenly over casserole.
Bake: Lower oven to 375°F / 190°C and bake 18–22 minutes until bubbling and golden. Broil 1–2 minutes if you want extra color.
Rest & serve: Let rest 5–10 minutes; garnish with parsley and serve warm. Store leftovers as described.
