preheat the oven to 400˚

line a baking tray with parchment or foil

place the bangers on the baking sheet, set aside until the sausages until the oven is hot, then bake the sausages for 10-15 minutes until they're hot and crispy

meanwhile, start a pot of water boiling to cook the potatoes

cut the potatoes and add them to the pot, cook until soft, then drain mash lightly, add 1/4 of milk and 1/4 cup of the butter and mash, add salt and pepper to taste-you can add the other 1/4 cup of milk if desired

while the potatoes are cooking heat the remaining butter in a deep frying pan over medium heat

slice the onions and cook them in the hot butter for a couple of minutes until they're translucent but NOT browned or caramelized

once they hit that stage pour the beef broth and the coffee in to deglaze the pan

scrape and stir up any stuck bits in the pan

stir or whisk for 1-2 minutes until the gravy starts to thicken

then reduce heat and just keep the gravy warm

add the crisped sausages to the gravy, stir to combine, and let them warm together for 1-2 minutes

serve the bangers and gravy over the mashed potatoes