In a large bowl, combine the dry cereal and protein powder. Stir to evenly coat the cereal.

In a small saucepan over low heat, gently warm the nut butter and honey. Stir constantly until the mixture is smooth and well combined.

Pour the heated nut butter and honey mixture over the cereal and protein powder. Stir until the cereal is fully coated and everything sticks together.

Transfer the mixture to a parchment-lined baking dish like a bread pan. Press it firmly into the dish using the back of a spoon or your hands.

Place the dish in the refrigerator for at least 1 hour, or until the bars are firm.

Once set, remove the mixture from the dish and cut it into bars or squares.