Combine Chex, Lucky Charms, pretzel sticks, and popcorn in a large bowl and mix well.
Melt white chocolate in a microwave-safe bowl for about 1 minute, then stir. If pieces remain, microwave in 10 second intervals, stirring each time, until smooth.
Pour about 3/4 of the melted white chocolate over the snack mix and stir well to coat everything evenly.
Line a baking sheet with parchment paper and spread the coated mixture into an even layer.
Drizzle the remaining white chocolate over the top.
Sprinkle with extra marshmallows, green M&Ms, and green sprinkles if using.
Place in the refrigerator for at least 2 hours or until the chocolate has fully hardened.
Break into pieces and enjoy. Store in an airtight container or plastic bags at room temperature.