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Monday, June 28, 2021

Baking Cookies in a Hot Car

How crazy is this? I used my car to bake a giant cookie and small loaf of bread on Saturday and a batch of smaller cookies and a loaf of bread on Sunday.

We're experiencing a heat wave in the PNW right now. Our house has stayed around 75 to 80 degrees F downstairs and upper 80s to low 90s upstairs. Our home is older and does not have A/C. As may be obvious, we're avoiding heating the kitchen at all. The heat should break overnight tonight. So, we mostly consider this a bit of something interesting with a little unpleasantness.

A combination of wanting some cookies, a super hot day, and mere curiosity got me to thinking about how I could harness the sun's heat to do a little baking outside. 

I tried to heat a dutch oven in the sun on our deck but it "only" got up to 135 degrees F inside. I went out to the front yard and checked the temp on the black driveway, but it wasn't any hotter. My daughters were washing the car for me, so I slipped the oven thermometer inside on the dashboard. It quickly rose to 165 degrees F, leaving me to think this might be the place to bake. Ultimately, the car's interior heated up to 175 degrees F on Saturday and 180 degrees F on Sunday.

I placed a potholder on the dash (so as not to do any damage from a heated metal pan), then place the pan of cookie dough on top. I left it all there for a little over 2 3/4 hours, from just after 1:00 to about 4:00 PM.

At first, the dough just looked melty and I could see one spot where it looked like butter was making a small puddle. As the afternoon wore on, the dough began to look more and more set. When I went to back the car up to get more sun (about 4:00 PM), I noticed that up close the cookie looked set. So, I touched the top and it was firm. By the way, the pan was too hot to handle without an oven mitt. I'm now waiting for the cookie to cool before I cut it into wedges.

So, I cut the big cookie into slim wedges.

Look, you can see those are baked cookie crumbs on that cut edge. 

The chocolate is still melty, so I'm chilling these for a bit to firm them up before removing the rest of the cookies from the pan.

After chilling, they came out of the pan nicely, and we all enjoyed them.

On Sunday, I tried individual cookies on a sheet of parchment paper in a small baking pan. My car oven got up to 180 degrees F at one point and remained there for over an hour. I baked these cookies for almost 4 hours, moving the car once towards the end to catch more sun on the dashboard. The steering wheel was so hot I could barely touch it.

For your information on baking car cookies --

  • I cut a chocolate chip cookie recipe in half, adding a bit more flour on Sunday and some oats on Saturday, trying to keep the cookies from spreading too much. I will be trying another batch of cookies today, adding just a touch more flour to the dough.
  • The car had been sitting in direct sun with the front windshield facing the sun for about 45 minutes before I checked the interior temp and put the cookie dough inside. I would guess you'd want to "pre-heat" your car oven for about 1/2 hour to 45 minutes before baking. All windows rolled up and front facing sun, if that's where you have a dark, flat surface for baking.
  • Place a fabric trivet or pot holder under the pan to protect the dashboard surface. And use potholders to remove the pan after baking. It will be hot.
  • Use some sort of oven thermometer to check the interior temp of your car. Food safety experts recommend perishable food not be held below 135 or 140 degrees F (I've read both figures on safe temps). And a cookie might not bake before the sun goes behind trees/buildings if the interior temp is below 160 degreesF.  I did my baking at temps ranging from 165 degreesF to 180 degreesF.
  • Leave the thermometer on the dashboard where you can read it through the windshield. Just like a regular oven, heat will escape every time you open a door. Unlike a regular oven, it takes a while to build up heat once again.
  • The best hours of the day for car baking are between noon and 6 PM for most areas.
  • While it felt really hot to us, the outdoor temp "only" rose to 95 degrees F on Saturday and 100 degrees F on Sunday. Some folks say you need a day hotter than 100 for car-baking. Mid to upper 90s look like they might work, too.
  • You can bake individual cookies on a large tray or in a cake or pie tin. I chose a cake pan on Saturday (which I greased first) as I originally had thought I'd try baking in a dutch oven set on my deck in full sun (see above -- not hot enough). Then, as I said, I tried individual cookies on Sunday, lining the pan with parchment paper. The individual cookies seem to hold together better than the cookie slices. However, I had to carefully remove them from the parchment with a thin metal spatula.
  • If your dash slants away from the sun, place your oven mitt/trivet so that the pan will be tilted very slightly toward the sun. You want the sun to directly hit the cookie dough.
  • I kept the doors to the car closed as much as I could, checking on doneness through the windshield.
  • In my experience this past weekend, car-baked goods don't brown like oven baked ones. Just something to know in advance. I found I had to look to surface changes to get an idea of whether or not something was baked.
I also baked a small loaf of bread both Saturday and Sunday. Saturday's bread was risen too much by the time I put it into the car, so it fell back. Still tasted okay, just not poufed up. for Sunday's loaf, I timed putting it into the car about halfway through rising. It continued to rise for about an hour while beginning to bake in the car. It fell back just a bit in the center before firming up. The end result was a dense layer beneath a bubble of crust. Upon cutting into it, the dense layer was a bit doughy. It was okay toasted, however. I'm going to try baking flatbread in the car today.

So, I took this heatwave as an opportunity to experiment. Seeing the positive side like this helped the time to pass and gave me something to look forward to instead of dread. 

More photos from Sunday's baking:

More hot weather cooking to come . . .


  1. This is so fun. We have a hot week here, also, so I may give it a try if I find the time. This reminds me of when I experimented with cooking an egg in the sun. You know the expression, "It's so hot, you can fry an egg on the sidewalk?" Well I thought I would test it out and tried various versions including the car, but none of them got hot enough to cook an egg." I later learned that you you temps in the 110+ to get it to work. Thankfully, it's never been that hot here.

    1. Hi Live and Learn,
      I've often wondered if that were possible with an egg and the sidewalk. Good to know it needs to be hotter. You saved me a mess on our driveway!

  2. Sounds like a fun experiment! Way to make the best of unpleasant temperatures!

  3. Did you think this up on your own or is this some sort of internet phenomenon that I am unaware of? Looks like you had fun with it, with a tasty treat to follow! I hope your heat breaks soon. Such weird weather we are all getting these days.

    1. Hi Kris,
      I thought of it, then went online to see if anyone else had done it. Lo and behold, this is a "thing". Today's batch of cookies and flatbread look the best of all three days. I think I've hit upon what will and won't work. We shall see at the end of the day.

  4. Boy, when life gives you lemons you sure know how to make lemonade lol. I’ve never tried car baking. We will have the heat starting today, lasting all week. We aren’t expected to get to 100, but we’ll see. No AC here either. It’s going to be great.

    1. Hi Diane,
      ha ha! That's a great compliment.
      I hope your heat wave is more bearable and you find something about it to enjoy.

  5. You never cease to amaze me with your creativity and resourcefulness! You go, girl!

    1. Hi Linda,
      Thank you! It's been an interesting experiment and now I know we could bake cookies in a summer power outage. I learned something!

  6. car + window screen= dehydrator

    1. Hi there,
      I've heard that about using the car as a dehydrator. I think you could do that on a less hot day, too, as dehydrating produce and herbs only requires the temp inside a car to reach about 145 degrees F. Lacking a window screen to use, I think a cookie or cake rake set over a baking sheet might also work. I'm going to try this later this summer. Thanks for the suggestion!

  7. That's awesome - I will keep that idea in my file (brain) because you never know when things necessitate something like that. I love self-reliant tips and that certainly fits the bill.

    1. Hi Ruthie,
      That's true -- you never know when any of our areas could begin rolling blackouts like they have in California. Or, just to keep from heating the kitchen on a hot day and still make something fun like cookies. Or even while camping.


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