Melt coating chocolate in a double boiler or microwave. Using a small pastry brush, completely coat cavities of a dessert cup chocolate mold. Allow to set and paint another layer of chocolate to ensure cups will not crack. Allow to set and remove from mold.
With an electric mixer on medium-high speed, beat cream until soft peaks form. Place in refrigerator until needed.
In a clean mixing bowl, with a clean whisk, beat yolks on high speed until pale and frothy.
Meanwhile, bring sugar, corn syrup, and water to a boil in a small, heavy saucepan over high heat, stirring to dissolve sugar. Continue boiling for about 1 minute. With mixer on medium-low speed, carefully pour hot syrup down side of bowl containing eggs. Beat on medium-high speed until slightly thickened, about 5 minutes. Beat in praline paste. Stir in melted chocolate, vanilla, and a pinch of salt.
Add one-third of the chocolate mixture to whipped cream; whisk to combine. Add remaining chocolate mixture, fold to completely combine.
If there are any lumps in your mousse mixture, pass through a coarse sieve into a large bowl; discard any solids. Refrigerate 1 hour or until firm.
Transfer mousse to a disposable pastry bag fitted with a large star tip. Pipe mousse into chocolate cups to fill; garnish with hazelnuts and shaved chocolate.