This is more of a tip, less than a recipe.
I have been making velvety yogurt in my oven since last year and I have just purchased a brilliant Magimix electric steamer. It obviously does a hell of a lot more, but what this steamer does to perfection is yogurt because it has a 40 degrees position. But oven or steamer, the recipe is the same and works every time:
Take one litre of the best, creamiest organic milk possible, one organic full fat yogurt pot (small Yeo Valley will do) and the same pot full of skimmed powder milk. Mix it all and whisk until smooth. Pour into a jug and then fill 8 to 10 yogurt pots or 6 jam pots. Put into your oven at less than or about 50 degrees or use an electric steamer such as mine. Leave for 10 hours and wake up to the creamiest, most delicious yogurt! Promise!
I do not like sugar in my yogurts but I do put a spoonful of orange blossom water. You can innovate with any other fragrance but this works best for us.
The trick is to use very good, full fat milk and use it at room temperature – I do not bother with heating it up anymore – unless you are lucky enough to use raw milk.