Didn't post yet a recipe for chocolate pastry cream but I recommend this recipe.. (homecookingadventure.com)
For chocolate pastry cream: In a large saucepan, whisk together sugar, cornstarch, and cocoa. (bakefromscratch.com)
Don't get me wrong, there is nothing wrong to allow yourself some enormous chocolate pastries from time to time, as long as it stays occasional! (delscookingtwist.com)