Step 1: Combine Wet and Dry Ingredients
In a large saucepan, combine the sugar, butter, milk, cocoa powder, and a pinch of salt. Heat over medium, stirring constantly until the mixture reaches a rapid, rolling boil. Boil for exactly 90 seconds to ensure proper setting, then remove from heat immediately.
Step 2: Mix in Oats and Peanut Butter
Once off the heat, quickly stir in the peanut butter until fully melted and incorporated, then add the vanilla. Immediately stir in the oats, ensuring all oats are well-coated with the mixture.
Step 3: Shape and Cool the Cookies
Using a spoon or cookie scoop, drop spoonfuls of the mixture onto waxed paper or a non-stick baking mat. Form evenly sized blobs to ensure uniform setting. Let the cookies cool completely at room temperature, about 30 minutes, until they are firm.