Slice the olives width wise. You can do this before you start or while the eggs are cooking.
Hard Boil the Eggs
Add twelve eggs (I add two extra for tasting but you don't need to) to a large deep pot and cover by 2 inches with COLD water.
Heat the water and eggs to boiling and then reduce heat to low and simmer for 14 minutes.
At 14 minutes, remove one egg from the pan, rinse under cold water, peel, and slice to check doneness. If done, remove the rest of the eggs to an ice bath.
Peel the eggs and set in a small bowl.
Slice, Scoop, and Devil
Slice each egg lengthwise, drop the yolk in a small bowl, and set the white onto the deviled egg tray. You may need to use a spoon to get the yolk separated from the white but it will mostly just drop out. You will want to clean your knife after each egg to prevent the transfer of yolk to the whites.
Mash the yolks with a fork until they are a fine powder-like consistancy. You can also use a food processor. If you do, pulse carefully so you don't make a puree!
Add the mayo and mustard to the egg yolks and mix well. Add kosher salt and pepper to taste. You will be adding an olive to the top, which is salty, so don't oversalt the yolk mix.
Fill the Eggs and Enjoy!
Load your cake decorator with the yolk mixture. Choose a tip for the cake decorator. I like to use a scalloped edge.
Fill each white with a good amount of yolk.
Add a sliced olive to the top of each deviled egg. Sprinkle lightly with paprika if desired.
Eat a deviled egg!
Put the lid on the deviled egg tray and store in the fridge for up to three days.