Preheat the oven to 200°C.
Boil 150g butter and 225ml water in a saucepan until the butter melts.
Remove from heat, add 225g flour, and mix well.
Beat in 6 eggs one at a time, season with salt, and cool slightly.
Pipe the dough into eight golf ball-sized portions on a floured baking tray.
Bake for 30-40 minutes until golden and firm, then cool on a rack.
Whisk 300ml cream, vanilla seeds, and 100g icing sugar into stiff peaks.
Simmer 200g sugar, 200ml water, and vanilla seeds for 15 minutes into syrup.
Add 50ml liqueur and 120ml espresso, then simmer until thickened.
Make a hole in each bun base and pipe in the vanilla cream.
Serve the profiteroles topped with warm espresso sauce.