Melt 2/3 of the white chocolate chips over a double broiler. Once melted, remove from heat and mix in the rest of the chocolate to temper.
Using 100m clear fillable ornaments, add 4-5 tablespoons of the melted chocolate inside one half. Close the mold and rotate the ball to evenly coat the inside with chocolate. Tap several times, if necessary.
Chill in the fridge for about 25-20 minutes.
Meanwhile make the sauce: in a pot whisk together water, sugar, cocoa powder, salt, and espresso. Stir over medium heat and allow to thicken.
Carefully release the chocolate ball from the mold.
Heat a flat-bottomed bowl or pan and gently press the chocolate ball in a circular motion. Once a hole appears, about 2 inches in diameter, set aside on parchment paper.
To serve, place scoops of ice cream and cookie crumbles in the center of a plate. Cover with the chocolate ball, and then drizzle the hot chocolate sauce over the top to melt the surface.