I made a batch yesterday and it's hard but not rock hard - still scoops with a spoon. Really nice.

I used 600ml cream (not 500ml), 6 egg yolks, 2/3 cup sugar, 1tsp salt & 1tsp vanilla.

I heat the cream in a pot with the sugar & salt until it's dissolved. I then add some of that mix to the egg yolks before adding it back to the pot.

Heat while stirring constantly until it thickens & coats the back of the spoon. You can strain it if you get lumps (from not stirring).

Cool before putting in the ice cream machine.