Prepare a pan with non-stick spray. I use a 10x8 pan because I like nice and thick treats but you can use a 9x13 also or whatever you have. Glass is best because they stick less and it's easier to clean.
In a large saucepot on medium heat, add the butter and melt completely. I always use a wooden spoon when making rice krispie treats, they are nice and stiff and clean pretty easily.
Once the butter has melted, add the marshmallows and stir constantly until they are fully melted and nice and creamy. Remove from the heat immediately.
Add the ube extract and fully incorporate it into the marshmallows.
Add the rice cereal and stir quickly to fully mix in. Pour the mixture into the prepared pan and push down with your spoon to spread it all out. Spray your hands with non-stick spray and push everything down to get it nice and compact (be careful because the mixture may still be hot!).
Sprinkle the top with a generous amount of sprinkles and push them down with your hands as well so that they stick.
Allow the treats to cool for at least 20 minutes before serving, longer if you can resist. Enjoy!
Notes
It's important to press the rice krispie treats into the pan so they pack in and stick together better. Spraying your hands with non-stick spray makes pressing the treats into the pan much easier and cleaner. Hot marshmallows are VERY sticky!
Allow the treats to cool completely before cutting into squares. You can also refrigerate them first. This will make them a little harder and easier to cut into.
Store any leftovers in a covered container for 2-3 days.
You can use any sprinkles you like or can find. If you can't find a mix with eyeballs, you can also buy them separately and add them to your mix.
To make clean up easy, soak the pot and spoon in hot water for a few minutes and everything will come right off!
Toy spiders make a great decoration, just make sure no one tries to eat them!