Brown Butter Vanilla Bean and Nutella Swirled Rice Krispie Treats

Bahan-bahan (20 porsi)

• 1 cup butter (2 sticks)
• 1 vanilla bean (the seeds scraped)
• 2 ounce bags mini marshmallows (10)
• 8 1/2 cups rice krispies
• 1 -1/2 cups nutella