Preheat oven to 350 degrees (F). Line your cupcake tin with cupcakes holders and set aside.
Mix all of the dry ingredients together in a large bowl. Add the softened butter and vanilla, mix until the batter resembles course sand. Add the eggs, one at a time, beating well with each new addition. Add the milk, and mix well. Lastly, if making funfetti cupcakes, pour in the sprinkles and mix by hand, gently.
Spoon the cake batter into the cupcake liners (filling about ½ way each) and bake for about 18-20 minutes or until a toothpick comes out clean. Let cool completely, and then frost.
For the vanilla buttercream frosting
sticks (8 ounces) unsalted butter, very soft
Using a stand mixer, beat the butter and confectioners sugar together (adding about ½ cup of sugar at a time until it has reached your desired sweetness and texture). Slowly mix in the milk (you may only need ? cup) and vanilla extract, beating until slightly stiff and well combined (for about 3 minutes). Refrigerate for at least 10 minutes and then frost the cooled cupcakes.
For the decorations/toppings
Now, decorate!! And have fun. . and let the kids help too!
For the monsters, put on the frosting, apply the candy corn and then the candy eye balls.