Step 1

Take two tablespoons of the total sugar and put it into a bowl along with the egg yolks, flour, cornstarch and salt - whisk to combine and then set aside.

Step 2

Put the remaining sugar into a saucepan with the milk and vanilla, slowly warm over a medium heat.

Step 3

When it begins to get warm, drizzle a small amount of warm milk into the egg yolk mixture and whisk, then add a little more, repeat until everything is together in the bowl, then pour the whole mixture back into the saucepan. It's important to do this slowly and gradually so you don't scramble the eggs.

Step 4

Keep heating the mixture, whisking constantly until it begins to thicken and boil. Boil for one minute. When it's ready you should be able to coat the back of a spoon and draw a line in it with your finger.. Remove from the heat.

Step 5

Pass the pastry cream through a sieve into a bowl to make sure there are no lumps. At this point, if you want to be precise, you can weigh your pastry cream to calculate how much butter to add for different uses (see notes or blog post above). But for a firm creme mousseline that sets like mousse, the quantities in the recipe card should work great.

Step 6

Cover with cling wrap (make sure the cling wrap is touching the surface of the pastry cream to prevent a skin forming) and let it cool completely. Don't place in the fridge at this point, just let it come to room temperature.

Step 7

Remove butter from the fridge about an hour before using. It should be room temperature but not too soft. Your pastry cream should also be at room temperature, it should not be warm any more from cooking, but you shouldn't have placed it in the fridge yet, so it will be perfectly room temp.

Step 8

Whip the butter on high speed until very pale and creamy - about 3 minutes.

Step 9

Add the pastry cream 1 tablespoon at a time, whipping on medium speed for 20 seconds in between each addition.

Step 10

Once all the pastry cream is incorporated, turn the mixer on high again and whip for a further minute.

Step 11

If you are pouring into a mould or pastry ring, do so right away before the crème mousseline has a chance to set.