In the 3-quart pot, add the potato chunks and add enough water to float the potatoes. Cover and bring to a boil, then reduce heat to medium, keeping the potatoes at a medium boil until fork tender, about 10 to 12 minutes. Drain well and keep in the pot.
Stir in the cream cheese and butter until they melt, then whip in the half & half with a hand mixer until the mixture is smooth and creamy. Stir in the parsley and chives.
Carefully cut a wide circle around the stem of each tomato and remove it, then use a melon baller to remove the seeds and juice, leaving an opening about 2-inches wide in each tomato. Divide the mashed potatoes among the tomatoes, filling each past the top of the tomato.
Place the tomatoes on a foil-lined backing sheet and broil in the oven or toaster oven until the top of the stuffing is lightly browned and the tomatoes feel a little soft, about 5 to 6 minutes. Remove and allow to cool for 2 to 3 minutes, then serve.