Step 1

To make the custard, mix a splash of milk in a bowl with the custard powder and caster sugar to form a smooth paste. Heat the remaining milk to just simmering, then add to bowl with custard powder mixture and whisk to combine. Return custard to the saucepan and slowly bring to the boil, then reduce heat and simmer for 2 minutes, stirring continuously, until custard has thickened.

Step 2

Pour into a bowl and allow to cool, then whisk through lemon butter. Cover with cling film, pushing it down to touch the top of the custard to prevent it from forming a skin. Refrigerate until you are ready to serve.

Step 3

Preheat oven to 180C. Line two trays with baking paper.

Step 4

Place butter, milk, water, sugar, salt and lemon zest in a medium saucepan and gently heat to melt the butter. When the mixture is just about to boil, remove from heat and add flour, stirring with a wooden spoon to combine. Return to heat and beat vigorously for 1 minute to cook flour. Place in a bowl and allow to cool for a few minutes, then gradually add the eggs, beating continuously, until you have a smooth, thick batter.

Step 5

Place tbs-sized balls of batter onto the prepared baking trays a few centimetres apart. Dampen fingers and carefully smooth over the tops.

Step 6

Bake for 20 - 25 minutes until golden brown and cooked through. They should feel hollow when tapped. Allow to cool.

Step 7

Cut pastry puffs in half and spread with lemon custard and then top with the other pastry half.