You won't believe how simple and easy this is.
What you need
- One metal tray
- One black tea towel
- OVEN MITTS
- Sunglasses, hat, sunblock
- One pyrex toughened glass bowl
- Plate with rim that matches rim of pyrex bowl
- Aluminium foil cupcake pattie cases
- Cupcake or muffin mix
- 3 mirrors or aluminium foil on cardboard reflectors
Place the metal tray, tea towel and pyrex bowl in the middle of the sunlight from the mirrors, so it warms up. This should be in a position on a table that is safe. out of reach of children, out of the wind, with space to put another tray, oven mitts down.
Adjust the mirrors to reflect the sunlight to the middle of the metal tray, it works best upside down with a mirror underneath it. Otherwise a bluestone or concrete tile.
Make the cupcake or muffin mix with a little less water than usual, so its a bit thick, not pouring runny. Use a scoop or spoon and knife to put the mixture into the patty cases, between 1/3 and 1/2 filled.
Place the black tea towel folded in half on the plate. It needs to go past the rim of the plate and the pyrex dish. Put the patty cases in a circle, with a bit of gap between each one on the tea towel. Match the pyrex bowl rim to the plate rim.
These mirrors are set up against the fence for afternoon cooking, facing northwest. In the morning, the side mirror is placed facing east. Small mirrors make up the other 2 sides, and are adjusted to ensure there is no overshadowing.
Place the cupcake cooker in the middle of the mirror array, careful to keep the pyrex bowl clear of the mirrors. The pyrex can get hot enough to crack any mirror it touches.
The cupcake mixture will start to rise, condensation will form on the insides of the pyrex bowl, and roll down the sides to the tea towel. The tea towel will wick the condensation and steam outside.
Cooking time will vary depending on the size and position of the mirrors. Let them cook for 10 minutes without lifting the bowl. The condensation will start to clear back to a thin steam film. Suddenly you may smell 'cooked' cake.
If the cover has gone dry, your cupcakes are completely dried out, they're toast, not burnt, just really DRY. Best to lift the lid a little earlier to check.
FOLD DOWN 2 sides of MIRRORS before going near the bowl.
Save your eyes, be safe, get your oven mitts on. If your cupcake bounces when you tap the top gently then they're cooked. Stick in a skewer to check if they are cooked all the way through. If it comes out with goo, then its not cooked yet. If it comes out clean, the cupcake is cooked.
The aluminium patty cases ensure that the cupcake is cooked evenly all the way through. The additional concentration of heat really accelerates the cooking process.
When you lift the pyrex dish use oven mitts, as it will be very hot. Leave the pyrex bowl turned right way up to cool down outside in a safe place. It will stay very hot for a few minutes. Don't subject it to temperature shock, don't put into water until completely cooled, as you risk it cracking, or worse, exploding.
The aluminium patty cases will hold heat for a while out of the solar cooker. If you take cooked cupcakes in the baking paper cases out of the aluminium ones, you can reuse them with more baking paper patty cases later.
Doing big batches requires lining up the plates, and I would suggest using 2 long mirrors set up as a trough, and sliding the plates along, so you have a mini production line, push 'em on through to the other side.
One last tip. You can increase the rate of roll off of the condensation in a couple of ways. Angle the plate at 10 degrees elevation, to incline the pyrex bowl dome to a slight slope. If you don't have to use the bowl for anything else, a few thin stripes of clear silicon in a mushroom pattern inside the bowl will help the condensation form into droplets along the edge and roll to the rim. If a big flat pyrex dish is your option for a large batch, then picking it up with the mitts and wiping down the inside may be your only option.
Happy solar cooking!
Youtube video to follow soon.