Add the sugar, milk, butter, and cocoa powder to a large sauce pan over medium heat. Stir occasionally until butter has fully melted and ingredients are combined.
Bring to a full boil, stirring often. Boil for 60 seconds.
Remove from the heat and stir in the oats, peanut butter, vanilla, and salt. Stir well to combine.
Use a small cookie scoop or dinner spoon to drop the cookies onto a parchment lined baking sheet.
Immediately pour the sprinkles over the tops of the cookies.
Let cookies set on the counter for 1 hour or in the fridge for 30 minutes to firm up before transferring to an air-tight container.