Preheat your oven to 180°C fan. Heat the olive oil in a frying pan over a medium-high heat. Add the bacon and onions, and season with lots of pepper. Fry until the bacon is slightly crisp and the onions are tender. Remove from the heat and set aside to cool.

Mix the self-raising flour, suet, salt and pepper in a large bowl. Gradually add the water and mix until a soft dough forms.

On a lightly floured surface, roll the dough out into a rectangle roughly 30x25cm. Spread the cooled bacon and onion mixture evenly over the dough, leaving a 2cm border around the edges.

Tightly roll the dough from the shorter end into a log shape. Brush the outside with beaten egg, then cover with foil, ensuring the foil isn’t touching the roly poly.

Place on a baking tray and bake for 35 minutes. Remove the foil and brush with any remaining egg wash and return to the oven for a further 30 minutes until the outside is golden and lightly crisp.

Season with flaky salt and allow to rest for 5 minutes before slicing and serving.