In a large saucepan over medium heat, melt the butter.
Once the butter has melted, use a wooden spoon to stir in the mini marshmallows and vanilla extract. Stir frequently until the marshmallows have melted.
Add the orange food coloring, starting with 5 drops and adding more until you get the desired shade of orange you want. Stir continuously for an additional 2 minutes to incorporate the food coloring and make sure all the marshmallows are melted.
Add the cereal and toss to coat. Allow the rice Krispie mixture to cool slightly off heat before forming the pumpkins.
Coat your clean hands in cooking oil or spray and roll the rice cereal into balls. You should get about 5-6 4 inch balls. One by one, place them on a nonstick surface like parchment or wax paper. Once you have all of them rolled, flatten the tops just slightly and use a butter knife to make vertical lines from top to bottom to represent the grooves in the pumpkins. Set aside to set and cool completely.
Once cooled, use a small amount of green icing to attach the tootsie roll to the top of the pumpkin and place the remaining green icing in a piping bag with a small round tip. Make vines with loops and twirls with the icing. Place the black icing into a piping bag and pipe jack-o-lantern faces on all or some of the pumpkins.
Let thjem sit for 5 minutes to allow the icing to harden before serving!