In large mixing bowl, dissolve the yeast over the water with 1 tsp of the granulated sugar. Let sit for 10 minutes until frothy. Stir gently.
In separate mixing bowl, combine sugar, flour, & sprinkles. Stir to combine.
Add oil, vanilla, & eggs to dry ingredients & stir to combine.
Pour yeast mixture into other ingredients & knead for 15 minutes by hand (or with proper mixing tools if you have them) until you form a ball shape.
Spray clean mixing bowl with baking spray & place ball of dough into the bowl. Cover with a damp towel & place somewhere warm until dough has doubled in size (roughly 3 hours). Make sure to punch dough down every 45 minutes.
Slice dough into 3 (or 6 if you want a double braided Challah) even ropes. They should be long & thin. Attach ropes at one end by squeezing them together & braid the strands together. Squeeze the other end together once braid is complete.
Line baking sheet with parchment paper & place braided challah on top. Cover with dishcloth & set somewhere warm (not hot) & let it rise for roughly 1 hour.
Mix egg wash together & brush over entire challah (excluding the bottom).
Preheat oven to 350 F. Bake for 15 minutes & repeat brushing the egg wash over the challah. Bake a remaining 15 minutes. Let cool 15 minutes at least.
In a microwavable safe bowl, microwave the frosting for roughly 30 seconds. Immediately pour over challah. Top with extra sprinkles, serve, & enjoy!