Preheat oven to 180C. Place pancetta in a single layer on a baking paper-lined oven tray and cook for 10 minutes or until crisp.
Meanwhile, melt butter in a frying pan over medium-low heat. Whisk together eggs and cream in a bowl and season to taste with sea salt and freshly ground black pepper. Add eggs to pan and cook, stirring occasionally, for 2 minutes or until eggs are almost set, then add green onion and stir through.
To serve, place a slice of pancetta in each roll, spoon in scrambled eggs and serve immediately.