The Big Cookie Project: Week 29

We'll have to record this week as a big fail. I've made these cookies before, and they just didn't seem to come out right, so I thought that maybe I would give it a shot for the Big Cookie Project.
This recipe goes WAY BACK. When I was in first grade and studying dinosaurs, our teacher had us practice our writing by writing a recipe. The title of the cookie recipe was "Dinosaur Droppings" (I don't know who would ever name a cookie that, because it makes it sound so unappetizing and sort of gross). Some of the ingredients were "crushed bone" aka sugar. It really kept with the whole dinosaur theme.
I had no recollection of writing this recipe until a while back I found it in a drawer and realized my mom had kept it all these years! We made the cookies and they turned out great. Well...time passed and I was wondering what the recipe was. My mom finally lost the "Dinosaur Droppings" recipe, so I was left to find the recipe online. It's not that the cookies taste bad, they actually taste okay, but they don't get firm. I don't know what I'm doing wrong, but I'm pretty sure they aren't supposed to stay in a sad little clump that I can't peel off the wax paper. Maybe you'll have better luck...
"Chocolate Oatmeal No-Bake Cookies"
Ingredients"
1 stick butter
2 cups sugar
1/2 cup cocoa powder
1/2 cup milk
1/2 cup smooth peanut butter
3 cups instant oats
1 tsp. vanilla
Directions:
1. Combine butter, sugar, cocoa powder and milk in a large saucepan and heat to a low boil. Stir until mixture is smooth.
2. Remove from heat and add peanut butter, vanilla and oats.
3. Drop by tablespoonful on wax paper to let harden up. Can be stored in a containter in the refrigerator.

This is the picture after just adding in the oats. I have to admit, it sort of does look like dino poop...or atleast what I imagine what dino poop would look like :)This is the final step after dropping them on to the wax paper. I had such a hard time getting a clear picture of the cookie. It was almost as if they were saying, "No, I'm ugly! You can do better!"
I'm thinking maybe I didn't boil the mixture long enough. This will bug me until I figure it out. If you have a solution or a recipe that works, I'd love to hear it. Good luck and happy baking!