Broccoli, Pancetta and Blue Cheese Gratin

Ingredients

• 1 large head broccoli (500g), cut into florets, stalks peeled, sliced
• 150 gram (4½-ounce) piece pancetta, diced
• 1 small brown onion (80g), chopped finely
• 2 tablespoon plain (all-purpose) flour
• 2 teaspoon mustard powder
• 2 cup (500ml) milk
• 120 gram (4 ounces) gorgonzola, crumbled
• 3/4 cup (50g) coarse stale breadcrumbs