Combine 200ml milk with 175ml boiling water and beat in the eggs.
Mix dry ingredients in a freestanding mixer, then add butter and egg mixture for 5 minutes.
Knead the dough by hand on a floured surface for several minutes and prove for one hour until doubled.
Divide dough into 16 sausage shapes on lined trays and prove again for one hour.
Preheat the oven to 210°C.
Bake buns for 9 minutes, swap trays, and bake for 4 more minutes before cooling.
Line a roasting tin with non-stick baking paper for the toffee.
Heat sugar, glucose, and 4 tablespoons of water until deep caramel forms, then cool and pulse into powder.
Cook milk, cream, yolks, cornflour, and 135g caramel powder until thick at 85°C.
Simmer marmalade ingredients for 1.5 hours until they reach 104°C and peel softens.
Cook apple compote ingredients for 20 minutes until fruit softens and liquid evaporates.
Whip double cream, vanilla, and icing sugar to stiff peaks for the Chantilly cream.
Slice buns and fill 8 with marmalade and crème pâtissière.
Fill the remaining 8 buns with apple compote and crème Chantilly.
Beat icing sugar with water, divide, color, and pipe onto the buns.