Method

1. Preheat oven to 350°F (180°C). Butter an 9×13-inch (3 L) baking dish.
2. In a large pot of boiling salted water, cook cauliflower for 5 min. Drain; set aside in bowl.
3. Meanwhile, cook bacon in a large skillet over medium heat for 5 min or until crispy. Remove cooked bacon and set aside on paper towels. Discard all but 2 tsp (10 mL) fat.
4. Add leeks to skillet; cook, stirring occasionally, for 5 to 7 min or until very soft and just starting to turn golden.
5. Transfer to bowl with cauliflower; add bacon.
6. In a medium saucepan, melt butter over medium heat.
7. Sprinkle with flour; cook, whisking, for 1 min.
8. Gradually whisk in milk.
9. Bring to a boil and reduce heat.
10. Whisk for 3 to 5 min or until smooth and thickened.
11. Whisk in Swiss, Parmesan and salt until cheese is melted.
12. Pour over cauliflower mixture, stirring until well coated. Transfer to buttered dish.

Topping

1. In a bowl, stir together breadcrumbs, cheese and butter.
2. Sprinkle over dish.
3. Bake for about 30 min or until golden on top and heated throughout.