Put eggs in cold water on stove top on high heat. Once water is boiling, let boil 1 minute. Turn element of stove off and let sit for 12 minutes. Drain, remove from stove and place eggs in cold water for 10 minutes, replacing with cold water if necessary. Peel and mash eggs.
Butter one side of sandwich bread pieces.
Mix all remaining ingredients in bowl.
Spread over 10 slices of bread. Assemble tops on sandwiches.