In a small saucepan put in the blueberries, maple syrup and lemon juice. Heat over medium and bring the berries to a gentle boil. Stir often so they don't scorch. The berries will burst and you will have a lovely sauce. Pour this into a bowl and put it in the fridge to cool for approximately 2 hours.

In a medium pot gently heat the cream and milk. Stir often and don't let it boil.

In a heatproof bowl (I used a large glass measuring bowl) whisk the egg yolks with the sugar and vanilla.

When the cream and milk start to steam, very gradually pour the hot cream into the egg yolks, whisking constantly. I add just a couple tablespoons first, whisk that and then add the rest of the cream, very slowly so that I don't get scrambled eggs.

Once you have gotten all the cream and eggs together in the bowl, wipe down the outside of the pot (if you spill a little like I do) and pour the cream and egg mixture back into the pot. Heat gently until it coats the back of a wooden spoon. About 10 minutes. It is a thin custard so the best way to test is run your finger through the cream on the back of the spoon. If it stays separated then it is done. If it runs back together then you need to cook it a little longer. It will also sound different when it is done as you stir it. It will be more sloppy sounding and less splashy - very technical I know.

When it is done, pour it into a heatproof bowl {note after publishing: pour the custard through a fine mesh sieve to catch any bits of cooked egg} and put plastic wrap right onto the surface of the custard to avoid it getting a skin. Put the bowl in the fridge and let it cool for several hours or over night. To speed up the cooling process you could do what I did - use two stainless steel bowls from a nesting set and put the custard in the smaller one and some ice water in the larger one. Just make sure that no water can get into the custard bowl.

When the custard and berry mixture is completely cool, stir them together and pour the blueberry custard mixture into the frozen bowl part of the ice cream machine. Let it run until you have ice cream. Mine makes it a bit soft serve and then it firms up in the freezer after I transfer it to a container with a lid.