Mix the eggs, yolks, sugar, cornstarch and vanilla well, then add to the half in half in a saucepan and cook on medium heat, stirring constantly until you can feel the mixture thicken noticeably. Take it off the heat and whisk to break up lumps, adding the butter at the same time. The mixture should get very thick, if it clumps a bit, pass it through a strainer or beat with a whisk.
Off the heat, mix in the paw paw puree and lemon, then transfer to a bowl to cool, placing plastic wrap on the surface to prevent it from forming a skin. Refrigerate the pudding until needed.
Finishing and Serving
To serve the pudding, whip the cream and tablespoon of powdered sugar until stiff peaks form. Spoon the pudding into four 1 cup ramekins, leaving ½ inch of headspace on top for the whip cream.
Cover the pudding with the whip cream and smooth the top with a pastry spatula. Sift on some powdered sugar, garnish each with a mint leaf if using, and serve.
Notes
In the recipe I call for paw paw puree, which you can purchase through Earthy Delights if you don't have access to fresh paw paw. Otherwise you'll want to remove the flesh from your paw paw, discard the seeds, and puree in a food processor. Be careful to work quickly pureeing your own paw paw flesh, since it will oxidize if left alone for too long. The other important thing to know is that the more heat you apply to paw paw, the less of it's perfume will be in the finished product. This is why the paw paw is added at the end in this recipe-different than most pastry creams, which is essentially what this is.