The product that I have been using for at least 15 years is the Solar Oven. This can cook anything that you can cook in a regular oven. Besides using it at home, I have taken it camping, and cooked frozen lasagna, cookies, cakes, breads, and casseroles. It is great. The temperature in the oven can get up to 375 degrees. Again with this, you need to turn it every 30-60 minutes as the sun moves. I have used this in the summer mainly but I have also used it in the winter. It may not get as worm but that just means you need to cook the food longer.
These are both great products and both can be found and purchased in numerous locations so shop around. If you don't want to spend the money, you can even find instruction on the web on how to make your own solar ovens and pots. HAVE FUN!!! It is a great feeling to be self-reliant!