Combine the cream and lavender flowers in a heavy medium saucepan and bring to a simmer then remove from heat.
Cover the pan and allow to steep for 15 minutes.
Next, in a medium mixing bowl, beat the sugar into the egg yolks until thickened and pale yellow.
Beat in the flour and set aside.
Strain the cream to remove the lavender flowers.
Slowly beat the warm cream into the egg yolks.
Now, pour the entire mixture back into the pan and place over low heat.
Stir constantly with a whisk, or wooden spoon, until the custard thickens slightly. (Don't let the mixture boil or the eggs will scramble).
Remove from the heat and pour the hot lavender custard through a strainer into a large, clean bowl.
Allow the custard to cool slightly, then stir in the rose water (if using).
Cover and refrigerate until cold, or overnight.
Stir the chilled custard, then freeze in 1 or 2 batches in your ice cream machine according to the manufacturer's instructions
When finished, the ice cream will be soft, but ready to eat.
For firmer ice cream, transfer to a freezer-safe container and freeze for at least 2 hours.
Top with heated lavender honey and honey granola (instructions below)