Combine butter and chives. Roll bite-size pieces of smoked salmon into 1" high cone shapes. Stir mascarpone cheese with chopped dill until fluffy.

 

Fit pastry bag with fine tube. Fill pastry bag with dill cheese. To assemble, spread chive butter on bread rounds. Place rolled salmon cones upright on bread rounds. Pipe dill cheese into center of each cone.

 

Garnish with small dill sprigs. Can be made few hours in advance and refrigerated. Before serving, let stand briefly to remove chill.