Add gelatin to a small cup or bowl and add brandy to gelatin.
Next, add the chocolate chips to a medium sized mixing bowl and also use a small pot on the stove top to heat the milk until it just starts to simmer.
And then, just as the milk starts to simmer, turn the heat down a bit, add the gelatin and brandy using a whisk to completely incorporate that and then pour the hot milk and gelatin mixture over the chocolate chips.
After a minute whisk the mixture and let the mixture cool down to room temperature, you can pop it into the fridge to help move it along -- while that is happening, use an electric mixer to whip heavy cream.
Whip that until it is nice and stiff but don't go too far.
Once the chocolate has cooled down to room temperature, add it to the bowl with the whipped cream and very gently fold them together so that the chocolate is completely incorporated.
At this point you could fill wine glasses with the mousse and serve it like that or add it to a plastic wrap lined 9x5-inch loaf pan and then cover that with additional layer of plastic wrap and put it in the fridge to set up for a few hours or overnight.