Place eggs in a saucepan; cover with water. Bring to a boil over high. Remove from heat; let stand 12 minutes. Transfer eggs to a bowl of ice water. Cool completely, about 5 minutes. Peel eggs; halve lengthwise. Carefully remove yolks, reserving whites. Whisk together mayonnaise and miso in a bowl until smooth. Add yolks, shichimi togarashi, and half of scallions. Place egg white halves on a platter; fill with yolk mixture. Sprinkle with sesame seeds, shichimi togarashi, and remaining scallions.