In a saucepan, bring the butter, milk and light cream to a boil.
In another bowl, combine the sugar, cornstarch and eggs in a bowl and whisk until ribbons form.
Once your butter, milk and cream boil, whisk in the egg mixture and bring to a boil again. Allow to cook for 1 minute past boiling.
Pour into a bowl and cover the surface with plastic wrap.
Chill at least 2 hours but overnight is optimal. When you remove from fridge, whisk to smooth out and add the rum.
For the Chocolate Ganache:
Heat the cream in a small sauce pan over medium heat. Bring just to a boil, as it's starting to bubble, but not froth, pour the chopped chocolate in and then whisk until nice and smooth.
Remove from stove and allow to cool for about 10-15 minutes or until you see it thicken up a little.
To Create Waffles:
Start with two Belgian Waffles, and slather the pastry cream on one of them. I make sure to push it down into the crevices of each waffle crater and then slather even more on top. Put the other waffle on top. It's ok if some escapes.
Pour the chocolate ganache over the top of the waffles and allow to slowly start dripping down the sides.