Slice 12 large hard-boiled eggs in half lengthwise. Gently remove the yolk and place yolks into a mixing bowl. Set whites aside on a serving platter.
Use a fork to mash egg yolks in the mixing bowl. Stir in 1/4 cup mayonnaise, 1 tablespoon dijon mustard, 1 tablespoon dry ranch seasoning, and 1/4 teaspoon black pepper until well combined. Taste and add salt if necessary.
Spoon filling into the centers of the whites or use a pastry piping bag to fill. Sprinkle the tops with 1 tablespoon minced chives. Chill in the fridge until ready to serve. Serve cold.
Notes
Some mustards and ranch seasonings are saltier than others. Your recipe may not need salt. You can stir this in last after tasting your filling to decide.