Put eggs into the cold water, have the water be an inch above the eggs. Turn on the stove, and let it boil. Once boiling, set a timer for 8 minutes. Take off the heat, and immmedieatly put into an ice bath. Let cool. Halve the eggs lengthwise and add the yolks to a food processor. Arrange the whites, cut side up, on a serving platter.
To the food processor, add the mayo, cream cheese, mustard, vinegar, scallions, and dill. Process until the mixture is smooth, creamy, and fluffy, scraping down the sides of the food processor bowl once or twice.
Taste and add more seasoning, as needed.
Spoon the filling into a piping bag (or a resealable plastic bag with the corner snipped) and pipe the filling into the skull mold. Put into the freezer for around 30 minutes. This will harden the egg mixture. When ready to serve, take the mold out and pop out the skull egg mixture. Place on top of the halved egg whites. Garnish with some edible flowers, and eat away!