For croquettes: In a large bowl, add all of croquette ingredients and combine to distribute ingredients thoroughly; refrigerate for 30 minutes (or longer) before using.
Heat 2 tblsps olive oil in a large non-stick skillet over medium heat.
Using a tablespoon (dipped in water), scoop out rounded spoonfuls of the croquette mixture and, using another spoon, push the mixture into the hot skillet; continue until you have filled the skillet with turkey croquettes; fry croquettes 5-6 minutes per side, until dark golden-brown; you may need to reduce heat slightly; remove as they are done to a glass baking dish; you will need to fry up in about 2 batches (maybe just into a third, depending on how big your skillet is); keep croquettes warm in a preheated oven while you make up the sauce.
For creamy-mushroom sauce: Increase heat under skillet used for cooking croquettes (do not clean it out in any way!) to medium-high and add the sliced mushrooms (do no add any more fat); allow the mushrooms to release some of their liquid and stir up tasty browned bits that are left in the pan from cooking the croquettes; add garlic and sauté mushrooms, stirring occasionally, until all the liquid they have let off has evaporated, about 9-10 minutes; add cream and cook until cream has thickened, about 10 minutes; pour sauce over turkey croquettes, sprinkle with minced fresh parsley and serve with hot buttered rice or noodles; this will make just enough sauce to coat croquettes; if you like loads of sauce, use more mushrooms and cream.