I recently tried out the Shake Shack Mud Pie custard, which is a Wednesday custard flavor during January. I tried to find a detailed description of it online - Serious Eats blogged about it before, and you can find the post here.
This custard was super chocolatey with the welcome addition of crispy chocolate wafer pieces on top. The only difference from the Serious Eats post is that mine were chocolate wafers and not Oreos, sadly. The chocolate custard was really rich and tasted slightly different from their regular chocolate custard.
If you're a choco-holic, make your way to a Shake Shack on Wednesday soon!