In a medium saucepan over medium-high heat, combine the sugar, milk, butter, and cocoa powder. Cook, stirring frequently until it reaches a full boil. Then allow it to boil for 1 minute without stirring.
Remove from heat and add in the quick oats, peanut butter, vanilla, and salt. Stir the mixture until well combined.
Using a medium spring-loaded cookie scoop, level, and roll about 1.5 tablespoons of the cookie dough and place it on the prepared baking sheets. Use your fingers to gently flatten the cookies. Allow to rest at room temperature until set and hardened, about 30 minutes before serving.
Notes
Storage: Allow your cookies to cool and firm completely, then transfer to an airtight container and store at room temperature or in the refrigerator. They will last for up to 5 days at room temperature or up to 7 days in the fridge. Freezing: Freeze right on the baking sheet, then transfer them to an airtight container or freezer-safe bag. They will last up to 6 months in the freezer. Thaw your no-bake oatmeal cookies at room temp for about 30 minutes.