Line a 9 x 13-inch baking pan with parchment paper.

In a large bowl, combine the rice cereal and oats.

In a medium saucepan over medium heat, stir together the brown sugar and honey until just boiling. Remove from heat and stir in the peanut butter and vanilla until well combined.

Pour over the dry ingredients in the bowl and mix with a wooden spoon.

Stir in the walnuts and let cool slightly before adding the chocolate chips.

Pour mixture into the prepared baking dish with a spatula, and press until it is evenly distributed.

Place into the refrigerator to chill until firm.

Slice bars into the desired size and serve.