Pick the leaves from the mint sprigs and chop roughly but thoroughly.
Place milk and vanilla into a Saucepan on medium low heat until just below boiling. Add the mint leaves, stirring to combine. Leave to infuse for 30 minutes, stirring occasionally to release the chlorophyll from the mint.
Meanwhile combine the eggs and the caster sugar and mix until pale.
Once infused, strain through fine sieve, and return to sauce pan. Bring the milk back up to just below boiling.
Add half the hot milk into the egg mix and stir to temper the eggs. Now pour the egg and milk mix into the remaining milk and stir constantly until it thickens into a custard, never letting the temperature rise above 86C. Allow to cool to room temperature.
Place peas into a blender or whiz with stick mixer until a puree. Strain through a fine sieve into the custard mix. Add the cream and combine.
Place Custard into the refrigerator until cold. approx 4 hours.
Churn in an ice cream machine as per instructions. Add in the chopped chocolate half way through.
Freeze and then serve.