Step #1 For filling, place mascarpone cheese in mixing bowl.
Step #2 Dissolve coffee in the rum.
Step #3 Add coffee rum & brown sugar to the cheese.
Step #4 Mix together well.
Step #5 Cover up with plastic wrap & chill until needed.
Step #6 Preheat over to 400°.
Step #7 Line 2-3 baking sheets with parchment paper.
Step #8 For cookies, cream caster sugar & butter together until light & fluffy.
Step #9 Add beaten egg & mix well.
Step #10 Stir in the flour & mix thoroughly until well mixd.
Step #11 Place mixture into a pastry bag with a ½ inch plain nozzle attached, or you could us a heavy-duty plastic bag & snip off a bout ½ inch from 1 corner.
Step #12 Pipe 28 small blobs onto the baking sheets, spacing slightly apart.
Step #13 Cook for 6-8 mins until firm in the center & just beginning to brown around the edges.
Step #14 Remove from oven & set aside to cool.
Step #15 To assemble, spread the filling over half of the cookies.
Step #16 Top with the other halves.
Step #17 Put chocolate & milk together into a small bowl & place over hot water.
Step #18 DO NOT OVERHEAT.
Step #19 When chocolate is melted stir vigorously to make a spreadable consistency.
Step #20 Spread the topping over the cookies & sprinkle with grated crushed chocolate flakes.