Using a food processor (or your fingers if you don’t have one), pulse the bread to form breadcrumbs. Set aside. Preheat your oven to 180C.
To a saucepan add the diced onion and butter. Fry until the butter is melted and onion is starting to brown. Add the dried sage, thyme, salt and black pepper and mix well.
Remove from the heat and add the breadcrumbs, mix well so they are fully coated in the onion mixture and transfer to a small baking dish. Press into the dish and bake in the oven for 20-25 minute.