Preheat oven to 220°C and line a tray with parchment.
Boil 110ml water and butter in a saucepan.
Beat in flour until smooth and cool slightly.
Beat in eggs one at a time until glossy and cool.
Pipe balls or lines of pastry onto the tray.
Bake at 220°C for 15 minutes, then 180°C for 35 minutes until golden.
Boil milk in a saucepan for the filling.
Whisk yolks, sugar, coffee, and flour in a bowl.
Whisk milk into egg mixture and simmer until thickened.
Sieve the filling, cover with film, and chill.
Whisk caramel milk into cold filling and chill.
Whisk cream, icing sugar, and liqueur into stiff peaks.
Melt glaze ingredients, boil, and cool for 5 minutes.
Glaze bun tops and sprinkle with chopped coffee beans.
Melt sugar until golden, then coat pecans.
Cool pecans on parchment and roughly chop.
Assemble buns with caramel filling, cream, and pecans.