Line a 9x13 inch baking pan with parchment paper, leaving an overhang on the sides for easy removal. Set aside.
In a large mixing bowl, combine the Rice Krispies, raisins, pumpkin seeds, almonds, and sunflower seeds. Set aside.
Place a large sauté pan or large pot over medium heat. Add the butter and allow it to melt.
Add the peanut butter, honey, brown sugar and a pinch of sea salt. Stir until smooth and well combined.
Bring the mixture to a light simmer and cook for about 5 minutes, stirring occasionally, until slightly thickened.
Remove the pan from the heat. Add the dry ingredients and toss until the Rice Krispies and remaining ingredients are fully coated in the peanut butter and honey mixture.
Transfer the mixture to the prepared baking pan. Press it down firmly and evenly until it is compact and sticking together.
Cover loosely with plastic wrap and refrigerate for at least 1 hour, or until fully set and cooled.
Lift from the pan using the parchment paper then slice into bars.
Store in an airtight container for up to 7 days.