Preheat the oven to 450°F/230°C/gas 8. Cook the pumpkin covered for about 15 mins in very little water. When tender, drain and purée. Melt half the butter in a frying pan, add the sugar & pumpkin and cook for about 10 minutes. Mix in the spices, orange peel & cheese. Remove from heat when cool, fold in eggs & rum, if used. Pour mixture into a buttered serving dish, press breadcrumbs & sugar into the top, dot remaining butter and bake until the top is crunchy & brown. Serve warm.