Line a cookie sheet or large cutting board with wax paper. Set aside.

In a large saucepan, combine the sugar, milk, cocoa powder, and butter. Stirring often, bring to a boil over medium heat. Let the mixture boil at a full, rolling boil for 90 seconds (be sure to set a timer!)

Remove from heat and stir in the peanut butter and vanilla extract until smooth. Add the oats and stir well to combine.

Using a medium cookie scoop (about 1.5 tablespoons), drop cookies onto prepared parchment or wax paper. You can flatten them into a thick disc shape using the bottom of a glass or leave them in mounds.

Allow the cookies to set before serving. They are normally hardened within 15 to 20 minutes.