Optional toppings: hot fudge sauce, chocolate chips, chopped nuts
Line a 9x5 loaf pan with aluminum foil so that it completely covers the pan and extends 2 inches above the pan.
Place the white chocolate, milk chocolate and dark chocolate in three separate bowls.
In a heavy-bottomed saucepan, heat the cream over medium-low heat until it is hot and simmering. Be sure to stir it often so it doesn't scorch.
Pour 1 cup of cream over the white chocolate, 1 cup over the milk chocolate and the last cup over the dark chocolate. Stir each of the chocolate mixtures until it is creamy and smooth, with the chocolate completely melted.
Add the instant coffee granules to the melted milk chocolate.
Allow the mixtures to cool for 5-10 minutes. Then place the melted chocolates into the refrigerator for 30 minutes to cool.
In the bowl of a stand mixer (or using a hand mixer), beat the milk chocolate mixture with the whip attachment on medium-high for 2-3 minutes. Watch it carefully and stop the mixture when it becomes thick like sour cream. Be careful not to overbeat. The colder the chocolate is, the faster it will whip up.
Spread the whipped milk chocolate in the bottom of the prepared pan. Place the pan in the freezer.
Rinse the mixing bowl and whip attachment. Repeat this process with the white chocolate. Again, be careful not to overmix. Watch the mixture as it whips and stop it as soon as it becomes thick and creamy.
Spread the white chocolate overtop the milk chocolate layer in the pan. Place the pan again in the freezer.
Rinse the mixing bowl and whip attachment. Repeat this one last time with the dark chocolate.
Spoon this mixture over the white chocolate layer and smooth the top.
Cover the top of the pan with foil and freeze until firm, at the minimum, 3 hours.
When you are ready to serve, lift up on the foil to remove the dessert from the pan. Invert the frozen dessert onto a serving plate and remove the foil.
Top with the optional toppings, if desired.
Slice and serve.
*The warmer your melted chocolate is, the longer it will take to whip. This is why it is best for the chocolate to sit for 5-10 minutes until it has cooled a bit to close to room temperature.