Line a baking sheet with parchment paper and set aside.
In a microwave-safe bowl, melt the milk chocolate chips in 30-second intervals, stirring between each interval until smooth.
Once melted, add the crushed pretzels, mini marshmallows, and chopped pecans (if using) to the chocolate. Stir until everything is evenly coated.
Using a spoon, drop clusters of the mixture onto the prepared baking sheet, about 2 inches apart.
Sprinkle a small pinch of sea salt on top of each cluster.
Refrigerate the clusters for at least 30 minutes or until the chocolate has fully set.
Once set, remove from the refrigerator and enjoy your delicious chocolate pretzel clusters.