Combine walnuts, brown rice crisps, oat cereal, quick oats, and chocolate chips in a bowl.
Over medium heat, bring walnut butter, maple syrup, brown rice, and salt to a quick simmer. Cook for 4 minutes, stirring constantly. Remove from heat and pour over dry ingredients. Stir quickly, coating all ingredients.
Pour into an 8x8 inch pan, circle or square, and use the back of a measuring cup to firmly press down and spread out evenly. You want the bars to be tightly packed.
Let sit for 1 1/2 hours before cutting. Store in a sealed container, for up to five days.