Weigh the eggs into a heat-proof mixing bowl and add the sugar and cream. Whisk thoroughly to combine, then place the bowl on a tea towel for grip.
Place the milk, vanilla and salt in a medium saucepan over a medium heat. Allow the milk to heat up, stirring regularly until it is hot and just below a simmer.
Take the milk off the heat and set the pot aside (we are using it again in a minute). Pour the hot milk into a jug with a pouring lip to make it easier.
Take your whisk in one hand and the jug of hot milk in the other. Very slowly pour the hot milk into the egg mixture, whisking as you go. This will slowly bring the eggs up to temperature so they are less likely to scramble.
Once you have poured all of the milk into the eggs, pour all of the mixture back into the saucepan. Place it over a low/medium heat. Cook, stirring constantly (I like to use a silicon spatula for this so I can keep the bottom from over-cooking) for 5 minutes.
The mixture should feel a little different as you stir – slightly thicker but not fully thickened. If you have a thermometer, you want the mixture to reach 70C/158F to be food safe. Worry more about the consistency though as the mixture reaches this temperature easily within 5 minutes. If the mixture has reached 70C but hasn't changed texture, this is fine too.
If the egg mixture starts to develop clumps, immediately take it off the heat and whisk very quickly. Transfer it from the pot it was in straight away to remove the residual heat. I find that lumps are processed out once the ice cream is ‘churned’, so don’t throw away a slightly lumpy mixture.
Allow it to cool a little before transferring to the 470ml Ninja Swirl and into the freezer. Freeze for 24 hours with the lid off. Freezing with the lid off helps ensure the mixture doesn't form a hump during freezing which can damage the machine.
When ready to consume, spin the ice cream using the SCOOP and ICE CREAM function. I recommend the scoop function for all cream based ice creams as the SWIRL function processes them for too long and churns the cream into butter.
If you want to make soft serve, allow the ice cream to soften for 5-10 minutes if necessary. Swap the lids and place the piping nozzle on before using the handle to pipe. Note that the machine can’t process the bottom bit of mixture and it tends to go a bit icy.
Return any leftovers to the freezer with the lid on.