Grate the carrot and put into a large bowl with the cereal, raisins and linseeds, if using.
Stir the peanut butter, maple syrup, vanilla, cinnamon and nutmeg together in another bowl until well blended. Pour the sticky mixture over the Rice Krispie mixture and stir well.
Press the mixture down into the prepared pan. Refrigerate for at least an hour and then cut into squares or desired shapes.
These are nice from the fridge, but I really like eating them frozen!