In a bowl of a stand mixer or in a medium bowl with a hand mixer, beat the egg yolks with ⅛ cup plus 1 tablespoon sugar until thick and lemon colored. Set aside.
Stir the cocoa powder into the hot water in a small bowl until smooth.
Melt the chocolate chips in a double boiler saucepan or over very low heat, stirring continuously. Remove when the chocolate is almost melted all the way and continue stirring to melt.
Pour the chocolate into a large bowl and fold the egg yolk mixture in. Next, add the cocoa powder mixed with water.
Wash and dry the stand mixing bowl and dry completely. Wash and dry whisk attachment if used.
Whip the heavy cream until thick, soft and fluffy. Do not over whip.
Wash and dry the bowl and whisk or beaters.
In the stand mixer bowl or a large bowl with a hand mixer, whip the egg whites with the whisk attachment, beginning on very low speed and increasing the speed to high as small bubbles appear. Shake in the remaining ⅛ cup plus 1 tablespoon of sugar, with the mixer on. Whip just until stiff peaks form. If you whip past this point, it will be very difficult to fold into the chocolate and aeration of the egg whites will be lost.
Fold the whipped cream into the chocolate, a half at a time, folding very gently.
Fold the egg whites into the chocolate cream mixture, ⅓ at a time, folding very gently. You do not want to overfold or stir to combine. Chill in the refrigerator until assembling the pie.