Step 1: Prepare the Pan

• Line a 9×13-inch baking pan with parchment paper or lightly grease it.

• Set aside while preparing the mixture.

Step 2: Melt the Chocolate Mixture

• In a large saucepan over low heat, melt the butter.

• Add white chocolate chips and stir continuously until melted and smooth.

• Remove from heat and stir in vanilla extract.

Step 3: Combine Dry Ingredients

• In a large mixing bowl, combine crispy rice cereal and mini marshmallows.

• Pour the melted white chocolate mixture over the dry ingredients.

Step 4: Mix Everything Together

• Stir gently but thoroughly to coat all ingredients evenly.

• Add in rainbow sprinkles and fold gently to distribute color without melting them.

Step 5: Press into the Pan

• Transfer the mixture to the prepared pan.

• Press it evenly into the corners using a spatula or clean hands.

• Top with additional sprinkles or marshmallows for a decorative finish.

Step 6: Cool and Slice

• Let the bars cool at room temperature for about 1 hour or refrigerate for 30 minutes.

• Once set, lift the bars out using the parchment paper and cut into squares.

• Serve immediately or store for later.