I'm making Kenji's ultra-fluffy mashed potatoes and I think I under-cooked the potatoes when I boiled them. After I passed them through the ricer and added milk and butter, there was a slightly grainy consistency. I'm having serious restaurant people over for Thanksgiving tomorrow (expat, no Thursday holiday) so I really can't screw this up. Are they salvageable, or do I have to start over? Thanks for any guidance that anyone can give.