Peel and cut potatoes into 1" cubes. Place in pot with cold, salted water to cover. Cook on high heat. Usually 20 to 30 minutes until done.
Mash potatoes in a large bowl or use a potato ricer over a large bowl to mash potatoes until few to no lumps remain.
With a whisk, mix in cream, truffle oil, salt and pepper. Result should be incredibly smooth mashed potatoes.
Place a sheet of saran wrap over a cookie sheet.
Take a 1/2 cup measuring cup and scoop mashed potatoes into it until filled with a smooth even top. Turn 1/2 cup up side down on the cookie sheet. Mashed potatoes should fall out of measuring cup in a somewhat hockey puck shape. Repeat until all potatoes are used, should make about 6 little puck shaped mashed potatoes.
Place potato pucks in the freezer for about 1 hour.
In a shallow bowl crack eggs and mix with a fork, breaking the yolks. Season with salt and pepper.
In a shollow bowl, a casserole dish works great, place panko bread crumbs.
Remove potato pucks from freezer. Dip in egg, ensure completely coated.
Place eggy potato puck in panko turning over, ensuring full coverage. Return to cookie sheet, repeat until all potato pucks are done.
Return croquettes to freezer for 30 minutes.
Check croquettes, if not fully covered by panko repeat egg and panko coating process and return to freezer for 30 minutes.
When croquettes are good and coated with panko. Heat oil in a large frying pan, oil should coat entire bottom of frying pan with 1/2 inch deep.
Once oil is heated place croquettes in oil, they should immediately start sizzling. If there is no sizzle or a weak sizzle your oil is not hot enough. Remove and wait.
Fry until golden brown, turn over and finish cooking.
Note: Please ensure the pan in not crowded. If you can only fit 3 at a time, that's all you can do, heat your oven to 200F and have a pan in there to keep first batch warm. Also, if you skip freezer process these will fall apart, the same goes for if your oil is not hot enough. You need both to be successful.