Combine the frozen raspberries and water in a medium saucepan over a low-medium heat. Cook until the raspberries are completely softened, mashing them up as you stir.
Place a fine meshed strainer over a medium sized bowl. Use a spoon to gently stir and push the raspberry juice and liquids through the sieve. This takes about 15 minutes of active time (I do it front of the TV).
By the time you have finished straining, you should have approximately 130g seeds leftover and around 380g raspberry puree.
Pour the raspberry puree into your 470ml Ninja Creami tub. Add the light agave syrup and stir to combine. if the mixture exceeds the fill line, remove a bit until it is on the fill line. I drink it from a spoon - it's absolutely delicious.
Place your tub (lid off) in the freezer for 16-24 hours, depending on how cold your freezer is (colder freezer requires less time to completely freeze the mixture).
Process the mixture on the sorbet function. I found processing it twice on sorbet created a lovely creamy texture.
Store any leftovers in the freezer with the lid on. Allow to thaw slightly before serving.