100g white bread, crust cut off and cubed
2 tbsp olive oil
flavourings (and see below)
Dry the cubes of bread out, a little, in a very low oven (less than 100°c), but don't let them colour. Cool. Meanwhile, whisk the oil and flavourings together in a large bowl. Drop the bread cubes in (all in one go) and stir until they are evenly coated-ish. Tip onto a baking tray and return to the oven to bake, slowly, for another 10-15 minutes, depending on your oven. You will be able to tell, from the delicious smell, when they are ready. Indeed, the smell will also tell you when they are burnt, so be alert.... Let them cool completely before using or storing, as this will retain the crunch.
As for flavourings, I mostly make my crôutons with smoked paprika, with cracked black pepper or with garlic and herbs. A pinch of salt helps bring the flavours together in every case except for my cheesy croutons (which are usually eaten with tomato soup), which I make using some grated parmesan mixed in after the oil and a little garlic.
Incidentally, one possible word of warning though. I cannot, and will not, countenance the use of crôutons as a 'nibble' under any circumstances. I was shocked recently, to be offered a dish of mixed olives (fine, lovely), a single, whole, pickled artichoke heart (hmm...) and some clearly industrially-prepared-and-bagged crôutons masquerading as 'tapas' in a pretentious bar. Okaaaay... rant over.