1. In a medium saucepan, combine the butter, sugar, and milk. Heat over medium, stirring occasionally, until the mixture comes to a rolling boil.
2. Once boiling, allow it to boil for 2 minutes exactly (set a timer). Avoid stirring during that brief boil, but you can gently swirl the pan if necessary.
3. Remove the pan from heat immediately after 2 minutes.
4. Stir in the instant pumpkin spice pudding mix, pumpkin puree, vanilla extract, and pumpkin pie spice. Mix until the wet ingredients are fully combined and smooth.
5. Gradually fold in the quick cooking oats, starting with 3½ cups. If the mixture seems too loose, add a bit more oats until it holds shape.
6. Using a heaping tablespoon or heaping small cookie scoop, drop mounds of the mixture onto parchment or wax paper, spacing them a couple of inches apart.
7. Let the cookies cool at room temperature until completely set, about 30–60 minutes (or refrigerate briefly to speed up setting).

Once firm, enjoy!