Preheat oven to 180° Celsius (conventional oven) or 160° Celsius (fan-forced oven)
Grease and line 6 cavities in a half-cup capacity muffin tray
Spread out bread slices on a benchtop
Using a rolling pin, gently roll over each slice of bread until it is approximately 3 or 4 mm thick
Spread with a thin layer of butter
Press each slice of bread into each muffin tray cavity. Press overlapping edges into one another, but don’t worry too much about holes or cracks in the bread
To make the custard, separate the egg yolks into a small bowl. Lightly beat them and set aside
In a small saucepan over medium heat whisk together the cornflour with 125 ml (half a cup) of the milk. Whisk until evenly combined and there are no lumps
Add the rest of the milk, sugar and vanilla essence while whisking constantly to prevent mixture from catching on the bottom of the saucepan.
Continue to whisk until mixture is hot and thickened a little, but not boiling. Remove from heat and slowly add the egg yolks, whisking constantly to ensure the custard is smooth
Return saucepan to medium heat and continue to whisk until custard is quite thick. Remove from heat immediately
Spoon hot custard into the bread-lined muffin cavities until each cavity is filled
Bake for 20 minutes
To serve, grate a little nutmeg over each pudding (optional)