Add the potato, carrot, broccoli and sprouts to a saucepan. Cover with cold water and set on a medium heat, bring to the boil then lower the heat and simmer for 8-10 minutes until the vegetables are soft and mashable.
Drain well and add to a bowl. Using a potato masher, mash the vegetables into a chunky mash. The vegetables should still be chunky and not too smooth. Add the cranberries, panko, Parmesan, garlic and onion granules and mustard powder. Mix well and season with salt and pepper to taste. Leave to cool.
Preheat the oven to 190°C and line a baking tray with non-stick baking paper.
When the mixture has cooled enough to handle, form into 18 small croquette shapes. Add the beaten egg to a bowl and the breadcrumbs to a second bowl. Dip each croquette into the egg then into the breadcrumbs, making sure to coat on all sides. Place onto the lined baking tray and repeat with the other croquettes.
Spray with low-calorie cooking spray and pop into the oven for 20-25 minutes, turning halfway through until golden brown. Serve 3 croquettes per person with a side of cranberry sauce or glug of gravy.