Make egg salad: In a bowl, combine parsley, chives, shallot, mayonnaise, mustard, pepper, lemon zest, and lemon juice. Add eggs and smash ingredients together using a fork. Season to taste with kosher salt.
Make arugula salad: In a medium bowl, whisk olive oil, lemon juice, and salt. Toss with arugula.
Make sandwiches: Split biscuits in half, smear tops with jam, and fill with egg salad and arugula.