Add sugar, butter, and milk to a medium/large pot and cook on medium heat.
Bring to a rapid boil for about 1 minute.
Remove from heat and mix in vanilla and peanut butter. Add oats, making sure they all get coated, and let cool.
Use a cookie scoop to scoop out the mixture and place it on wax paper (or parchment paper). Let set until cool.
Notes
STORE Peanut Butter No Bake Cookies in an airtight container at room temperature for up to one week. You can also FREEZE them for up to 3 months; layer them with parchment paper to prevent sticking.To enjoy from frozen, let them thaw at room temperature for 20-30 minutes. They are best enjoyed at room temperature or chilled.