Inspired by the Boston Globe Magazine's Roasted Punched Potatoes (recipe probably paywalled), I smashed my own potatoes. (Upon reviewing the magazine photo, it seems I punched mine rather less genteely than the recipe called for.)
The trick is to bake them twice -- bake whole potatoes until very soft; smash with the bottom of a glass; and then drizzle with oil, salt, and pepper and bake again. The recipe called for 80 minutes of baking in all, which seemed excessive for a weeknight, so I did the first bake in the microwave (fork potatoes; microwave 5 minutes, flip over and microwave another 5 minutes; add minutes until done). The second bake is in the oven at rather high temperature (I did 475) to crisp up the edges.
If I had it to do over again, I wouldn't smash the potatoes quite so flat, for more fluffy soft potato between the crispy bits. I ate mine plain, but either ketchup or baked potato toppings (sour cream, cheese, bacon, chives) would be nice.
(Local social media celebrity Steve Garfield has a more faithful walkthrough of the Globe recipe.)