Scoop about 1 Tablespoon of leftover mashed potatoes (that have been chilled in the fridge overnight, if possible) and roll into balls.
Press each ball down a bit to flatten and place them on a tray that fits in your freezer.
Place your tray into the freezer and flash freeze until almost solid.
Once frozen, get your toppings ready (if any) by dicing them up into small cubes. I love to use cheddar and chorizo (or bacon!) here.
Take a small amount of toppings (one or two little cubes of cheese/meat) and place smack-dab in the center of your little potato disc. Then, start to gather the sides together to enclose the whole thing. You're basically sealing the toppings inside. Remember for the stuffing - less is more here!
Place each disc back onto your freezer tray and pop into the freezer to solidify one more time! You basically just want them firm enough to handle so you can dredge them without everything falling apart.
Prepare a dredging station with three shallow bowls. One should have all purpose flour, the second should have beaten egg and the third is your bread crumbs.
Dredge each potato nugget as you would any other fried food. First, coat in the flour mixture. This will help the egg adhere to the nugget!
Next, dip your nuggets into the beaten egg. Make sure to let any excess mixture drip off.
Lastly, coat your nuggets completely in the bread crumbs. This is where the nice crunch will come from so make sure you coat each nugget evenly.
At this point, if the nuggets have gotten too warm from the environment, you can refrigerate or freeze them until firm. If they are too soft, they will fall apart when frying!
Heat frying oil to 350F and fry your potato nuggets until golden brown. Remember, everything is already cooked so you just want to fry until you get a nice, crispy exterior and a warm, melty middle! This won't take very long. Make sure to move them around as they fry and keep an eye on them so they don't burn.
Remove potato nuggets with a spider strainer or slotted spoon onto paper towels to absorb any excess oil. Personally, I like to use good ole brown paper bags instead of paper towels.