Preferably the day before, crumble the stale bread into small pieces and cover with a damp kitchen towel so it firms up slightly.
Dice the ham/bacon and the two slices of bread.
In a large pan, heat 4 tbsp olive oil and fry the bacon and the unpeeled garlic cloves until crisp, then remove them. Fry the bread slices in the same pan and remove them too.
Stir the paprika and a little salt into the remaining oil, add the breadcrumbs, and fry until golden brown, stirring constantly - this can take up to 30 minutes.
Return the bacon, garlic, fried bread and grapes to the pan, toss, and serve hot.
Traditionally it can also be served with fried eggs, thinly sliced chorizo, radishes and crushed green olives.
The leftover hardened breadcrumbs can be eaten the next day with milk for breakfast.