First, I line a large sheet pan with parchment paper. This keeps the chocolate from sticking and makes cleanup super easy. Then I gather all my cereals, pretzels, and M&M’s in a large bowl.
I gently stir together Corn Chex, Rice Chex, Cheerios, pretzels, and 1 cup of M&M’s. I like to stir slowly to avoid crushing the cereal pieces.
In a microwave-safe bowl, I combine 3 cups of white chocolate chips with 1½ teaspoons of oil. I melt the chocolate in short bursts, stirring in between to prevent burning.
I pour the melted chocolate over the cereal mixture and quickly fold everything together. Working fast ensures the chocolate doesn’t harden before every piece is coated.
I transfer the coated mix to the prepared sheet pan and spread it evenly. I top with the remaining M&M’s and optional sprinkles. For an extra touch, I melt the remaining ¼ cup chocolate, pipe stripes over the top, and let it firm.
I let the mix sit at room temperature or in the fridge for 10–20 minutes until the chocolate hardens. Once firm, I break it into bite-sized pieces.
This mix is ready to enjoy immediately or package as a gift. I like storing it in an airtight container to keep it fresh.