In a large mixing bowl, combine the shredded turkey, chopped spinach, leftover stuffing, cream cheese, Parmesan cheese, garlic powder, onion powder, thyme, salt, and pepper. Mix well until all ingredients are thoroughly combined.
Scoop about 0.125 cups of the mixture and shape it into small oval or round patties. Place the formed croquettes on a parchment-lined baking sheet. Repeat until all the mixture is used.
In one bowl, beat the eggs; in a second bowl, place the breadcrumbs. Dip each croquette in the egg, letting the excess drip off, and then roll it in the breadcrumbs, ensuring an even coating.
In a deep skillet or frying pan, heat about 1 inch of oil over medium heat. You can test if the oil is hot enough by dropping a small piece of bread into it; if it sizzles, it's ready.
Carefully place a few croquettes into the hot oil, being sure not to overcrowd the pan. Fry for 3-4 minutes on each side or until golden brown. Use a slotted spoon to remove them and transfer to a plate lined with paper towels to drain excess oil.
Serve the croquettes warm with a dipping sauce of your choice, such as honey mustard or a spicy aioli.