In a stand mixer fitted with the paddle attachment, mix together 1 pound brownie mix and 4oz water. Mix according to bag directions. Reserve.
In a stand mixer fitted with the whip attachment, mix together 4oz water and 3oz meringue mix, whip to stiff peaks. Fold with reserved brownie mixture. Spoon batter into tart shells and bake in a 350F oven until just set all the way across (8-12 minutes).
Tart is best served warm or reheated in the oven to warm for a few minutes.