Line a 20cm square tin with baking parchment, leaving a little overhang for easy removal.
In a small saucepan, gently warm the peanut butter, honey, vanilla extract and salt over a low heat, stirring constantly for 2-3 minutes until smooth and well combined – do not let it boil.
Tip the rolled oats, mini chocolate chips and dried cranberries into a large bowl and stir to combine.
Pour the warm peanut butter mixture over the oats and stir thoroughly until everything is evenly coated.
Transfer the mixture to the prepared tin and press it down very firmly and evenly with the back of a spoon or a spatula.
Chill in the fridge for at least 2 hours, until the bars are firm.
Use the parchment overhang to lift the set mixture from the tin, then place on a chopping board and cut into 12 bars with a sharp knife.