Delicious! 
Boiled the potatoes, drained them, and put them back in the pan for 5 minutes to cook / dry out. I also preheated my cookie sheet, so when I smashed the potatoes, they dried a bit more right away. 
I melted my butter and brushed on the potatoes. Used a splash of onion infused olive oil, too. 
Popped in the oven at 425. I put a little shredded parmessan cheese on in the last few minutes. 
Nice and crispy and absolutely delicious.