Preheat oven to 220°C (200°C fan) or 425°F. Line a baking tray with parchment.
Drain and rinse chickpeas, then dry thoroughly with a kitchen towel, removing loose skins. Moisture is the enemy of crispness.
Spread chickpeas in a single layer on the tray. Roast 20 to 25 minutes, shaking halfway, until dry and lightly crisp.
Cool completely on the tray, uncovered for at least 15 minutes. They'll continue to crisp as they cool.
Melt chocolate in the microwave in 20 second bursts, stirring between each, until smooth (or melt over a pan of barely simmering water).
Stir the peanut butter into the melted chocolate until combined.
Add the cooled chickpeas and nuts. Stir gently until well coated.
Spread onto a parchment-lined tray or plate in an even layer. Sprinkle with flaky salt, if using.
Refrigerate until firm, then break into pieces and serve.
