Step 1

Butter a 13x9" baking dish. Toss puffed cereals, oats, and dried fruits, nuts, seeds and/or coconut (all mix-ins except chocolate chips) in a large bowl with your hands to evenly distribute.

Step 2

Bring brown sugar, honey, salt, and 4 Tbsp. butter to a boil in a small saucepan and let cook 1 minute. Remove from heat and whisk in nut butter and vanilla until smooth. Drizzle over puffed rice mixture and stir with a large rubber spatula until everything is evenly coated. If using chocolate chips, let mixture cool about 5 minutes before mixing in.

Step 3

Scrape mixture into prepared dish and press and compact down into an even layer with buttered hands. Let cool at least 1 hour before cutting into bars.

Step 4

Do Ahead: Bars can be made 1 week ahead. Store airtight at room temperature.