01 -
Preheat the oven to 350°F. In a food processor, combine bread and Parmesan. Pulse until coarse crumbs form, about 3 to 4 times; set aside.
02 -
In a large saucepan with a lid, melt butter over medium heat. Add flour and cook, whisking constantly for 1 minute. Gradually whisk in milk until smooth.
03 -
Add cauliflower florets to the saucepan, season with salt and pepper. Bring to a boil, then reduce to a simmer. Cover and cook for about 5 minutes until the cauliflower begins to soften.
04 -
Remove the saucepan from heat and gradually stir in the grated Gruyère until melted and combined.
05 -
Pour the cauliflower mixture into a 2-quart baking dish and sprinkle with the prepared breadcrumb mixture.
06 -
Cover the baking dish with aluminum foil and bake for about 20 minutes, until the cauliflower is tender.
07 -
Remove the foil and bake for an additional 20 minutes, or until the breadcrumbs are golden brown. Serve hot.