Preheat oven to 250°.
In a large mixing bowl, mix the confectioner's sugar into the yogurt one cup at a time with a hand blender.
Using tongs, chopsticks or tweezers, dip the pretzels, one at a time into the frosting and place them on the wire cooling rack.
Place a baking sheet under the wire rack to catch the excess frosting that will drip from the pretzels.
Once all pretzels are coated, Top with sprinkles if desired. Then, turn your oven off and place the wire rack and baking sheet in, leaving the oven door slightly open. The excess heat will help the frosting dry without leaving the pretzels soggy.
Allow frosting to harden for 3-4 hours, remove from oven, and store yogurt covered pretzels in an airtight container for up to 3 days.