Begin by preheating the oven to 350°F, then place paper cupcake liners into the baking tin.
Mix cake mix, water, oil, and egg whites with a stand mixer or handheld mixer on medium speed until fully blended.
Gently spoon cupcake batter into liners, filling them halfway. Bake for 15-18 minutes until cupcakes are golden and a toothpick comes out clean. Allow for complete cooling.
Keep cupcakes in their liners, core out the center (about the size of a quarter) with a knife or decorator icing tip, being cautious not to cut too deep or harm the liner. Keep the cupcake tops open for the cream.
In a medium-sized mixing bowl, use a handheld mixer to blend heavy cream and instant pudding mix. Beat until the pudding thickens. Cover with cling wrap and refrigerate to fill the cupcakes.
In a heat-safe small bowl, microwave the heavy cream for 2 to 2½ minutes. It's crucial that the cream is hot when you pour it over the chocolate chips.
Once the ganache has cooled, use a stand mixer or handheld mixer to whip it for 1 minute until fluffy. If the ganache is too stiff, you can incorporate ½ tablespoon of lukewarm heavy cream.
For the cupcake's ganache frosting, use a decorator's frosting bag with a larger frosting tip (like Wilton tip 2D or 2A, or a generic large decorator's tip). If you lack these tools, opt for a gallon-sized Ziploc bag with a small corner cut for an alternative.