Eclair: Custard Sauce Filling

Eclair: Custard Sauce Filling


45g butter

50g water

50g milk

1g salt

2g sugar

60g cake flour

110g egg


Notes: By cake flour, I mean low protein flour, which normally contains 7-9% protein (Mine is around 8%). Not self-rising flour.


Custard Sauce:

1 egg yolk

15g sugar

12.5g cornstarch

125g milk

10g unsalted butter




  1. Heat and boil water, milk, butter, sugar, and salt.
  2. Turn off the heat, add in cake flour; stir hard until all the ingredients come together. Turn on the heat (keep it medium), and keep stirring until some thin film forms on the bottom of the pan.
  3. Transfer the dough to a clean bowl, let it cool down a little bit, and then use a hand mixer, beat while adding egg into it until it gains a very smooth and silky texture.
  4. Put the batter into a pipping bag with a pipping tip and start to pipe out eclairs.
  5. Dust them with powdered sugar. (3 times)
  6. Preheat the oven to 374℉(190℃) and bake for 20 minutes; then set the oven to 347℉(175℃) and bake for 20 minutes. Take the cream puffs out of the oven; let them cool down on the cooling rack.


Custard Sauce

  1. Add sugar into the egg yolk, whisk until sugar slightly dissolves. Add in cornstarch and milk, whisk until smooth.
  2. Heat and keep stirring the mixture until thickened. Add in butter, and stir hard until well combined.
  3. Transfer custard sauce into a clean bowl, cover the sauce with plastic wrap, and set in the fridge to cool down.
  4. Take the sauce out, whisk it smooth, add in 80g heavy cream and 12g sugar, whisk until form stiff peaks. Put them all in a piping bag, and fill the éclairs or any cream puffs with it.
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