Mix a pack of mr mash up with a teaspoon salt and 500ml boiling water til it’s like a hard dough. Put a dollop onto sheet of cling film fold film over and roll outuntil thin 

Peel back half film and fill with choice of filling then using film

roll over into sausage roll shape. For fillings I mashed some potatoes then to one batch I added the mash and half a tin of tuna, grated cheese a squidge of Tom puree to another cheese and onion , and the last sausage meat 
Brush with beaten egg and cook gas 7 til browned and crisp.