Add the Splenda to the ground flaxseed, mix well, melt butter, add dry ingredients. Transfer to 7 inch cake tin with loose base. Press down and chill in fridge at least 30mins.
For the filling, combine the cream cheese, Splenda, lemon juice and mix well. Beat the cream until stiff. Fold the cream into the cheese mix, pour over the base, set for at least half day, or better still 1 day.