This article is taken from the booklet: Solar Cooking by Angela ‘ARNie’ Grabowski order your copy here- http://chezcrochet.com/page92.html
AN OVEN THERMOMETER IS A MUST. You will toss more attempts in the trash, if you try to bake with temperatures that are too low.
I don’t recommend putting an air-tight lid on baked goods, since the moisture escaping from the recipe really needs to move away from the batter, instead of being trapped on top of it.
For novice solar cooks, I recommend using quick bread recipes until you have a solid knowledge of how well your oven works. One step further, I recommend using quick bread recipes with either soured milk, buttermilk, yogurt, or acidic juices. These will inhibit bacterial growth at the lower temperatures. (See recipes at end of book)
Smaller recipes are better suited for solar cooking- no more than 2 cups of flour or dry ingredients for a coffee cake, ginger bread, brownie, or corn bread recipe.
Solar Cooking is well suited for Whole Wheat flours, since solar cooking requires longer cooking times, the flours get the toasting they need to taste wonderful.
After 1 hour in the solar oven, or when the quick bread is firm to the touch, you might want to put a Black Lid on your brownies to prevent over browning on top. The Black lid will help protect the top surface, but still delivers heat to the top of the recipe to help its continued cooking.
The Clean Knife/Toothpick trick simply hasn’t worked for me. I’ve had numerous recipes where the toothpick was clean, but the interior of the batter was still ‘gooey’ or doughy. Put your quick bread in the solar oven after it has reached 250F empty, then leave it for at least two hours.
For me, dried fruits have worked better, than fresh or frozen or canned. The added moisture from the fruit cannot evaporate at the lower temperatures, and makes for a gooey cake, no mater how long it cooks.
Finally, I have had much better luck with parchment paper, than cooking spray to prevent sticking. The bottom of the recipe won’t get quite as browned, but at least it won’t, stick to the pan.
Copyright Angela 'ARNie' Grabowski 2009