Preheat oven to 200°C fan forced. Bring a large saucepan of salted water to a boil. Add Fioretto® cauli blossom and cook for 1 minute until stems turn green. Drain well. Arrange in a single layer onto a greased shallow tray or baking dish.
Melt the butter in a medium saucepan over medium heat until foaming. Remove 1 tbs to a bowl. Add flour to the pan and cook, stirring for 2 minutes or until the mixture bubbles. Remove from heat and stir in the mustard. Gradually add the milk, whisking constantly until smooth. Return to medium-high heat and cook, stirring for 5 minutes or until sauce comes to the boil. Remove from the heat. Stir in the cheddar and season. Spoon over the Fioretto® cauli blossom.
Add the panko crumbs to the reserved melted butter and mix well. Spoon over the Fioretto® cauli blossom and bake for 8-10 minutes or until light golden. Serve.