Melt the butter and add to the water and salt. Combine with both flours. Leave to rest overnight. Give 4 double folds.
Make a pastry cream and add the cold butter and hand blend. Place the mousseline in the chiller. When very cold place the mousseline in the kitchen aid and whip until light.
Heat up the cream with the small amount of sugar and pectin and leave to infuse with the vanilla bean. Make a caramel (dry method) with the white sugar (only) and when amber caramel coloured, add the brown sugar and dissolve. Cook down the caramel with the hot cream. Hand blend. Cool down and lightly mix with the spatula before piping onto the puff pastry.