Baking Brownies in Mason Jars

I just spent a few hours with the amazing youth that I teach at church.  We had a party that included lunch and -of course -DESSERT!  The party had a country girl theme, so I wanted to keep the dessert something country feeling.  While I was planning the party, I remembered something I had heard about a couple of years ago: baking brownies in mason jars and sealing them.


I’m a big fan of Mason jars, and I just can’t get enough of the wide-mouth shallow jars!  I keep a few on hand because they’re so pretty, and they are perfect for this.

Here’s a affiliate link to the jars I use!

All you’re going to need is about 9 jars (give or take) and a brownie mix.
Mix up the brownie mix according to the package instructions. Preheat the oven to 400 degrees. Sterilize your jars (some people boil them, but I just wash them with hot soapy water, rinse them in hot water and then dry them). GREASE the insides of the jars -I used PAM. Fill the jars 1/2 full with brownie batter.
That’s my son. He was dying to get his hands on some brownie batter. Put the jars on a cookie sheet and bake them for about 30 minutes (mine were done in about 25 -keep a close eye!).
While they’re in the oven, start some water boiling on the stove top (I use a small frying pan -the kind you use to cook one egg in) and boil the lids.
Pull the lids out of the water. I love my handy-dandy magnetic thingy.
Place the lids on the hot fresh-from-the-oven jars and screw the bands on. I had to carefully pick each jar up with a hot pad and then screw the bands on. Be very careful! They’re so HOT!
As the jars cool, they will automatically SEAL and the brownies will keep on the shelf for up to a year! Not like brownies ever last that long at my house. They’re gone within the week (and by “week” I mean three days. tops).
I tied raffia to the lids and put them next to a bowl filled with lentils. I put forks poking up out of the lentils, and the girls LOVED them! It was fun to watch them all eat out of their own personal little jar. After their brownies were gone, we washed their jars and filled them up with the butter they made that morning and they got to take it home.

Very Important Note: This recipe can be used with bigger jars. This recipe can be used with boxed cake mixes following the same instructions save one: decrease the oven temperature from 400 to 350. DO NOT frost the cake or brownies before sealing!!
These make for GREAT gifts and they ship easily (so long as you’re careful about packing glass). Missionaries love them. Military personnel love them. Visiting Teachers love them. Husbands love them. Women love them. Children love them. If you want my address to send me some, I’ll willingly oblige.

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36 Responses to Baking Brownies in Mason Jars

  1. Ashley M says:

    Those are the CUTEST jars? I’ve never seen a mason jar that shape. I need to get some pronto!

  2. LuAnne :) says:

    Such an AWESOME idea! I think I’m going to have to try it out!

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  4. kathy says:

    Hi , this is a great idea. Can you please tell me where I can purchase this type of jar??
    plan on making these and sending to my son in Afganistan
    Thank you

  5. Jessica says:

    I’ve heard over and over again about Cake in a Jar, but my boyfriend (overseas on deployment) is not a fan of cake, but BROWNIES. I’m glad to see this is a tried and true recipe. I’ll be baking and mailing soon! Thanks!

  6. Rowena A. Morgan says:

    Thank you SO MUCH for this idea! My husband is in the Navy, and on a Submarine that doesn’t surface during underweighs, so anything that is going to be sent with him has to be sent from the get go! This would be a GREAT idea for Halfway Boxes, since he always says the worst part is leaving my baking! THANK YOU AGAIN!

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  8. Ingrid Russell says:

    Why can’t you add frosting to this ? Can you add marshallows to make little ghost?

    • Alicia says:

      The frosting would definitely get rancid unless you ate the brownies within the day (or maybe the next day!) and I don’t know about the marshmallows…

  9. Nicole says:

    Thanks for the DIY. My son is deployed and asked for brownies in a jar. I said self, you can do this, you just need a little guidance. I love the fact that I can use box brownie mix. All the other recipes I found on line were making it from scratch. I am a working mom and need to make it look I made it from scratch. Thank you and I know my son will thank you too!!

  10. Mary says:

    Made them for my daughter’s bridal shower AND for a group of students at our University! Easy, inexpensive and fun to eat! Thanks for sharing!

  11. Joanie says:

    I am going to make brownies in a jar for our my churches bake sale in April, along with my cake in a jar,. Do you think bread in a wide mouth jar can be made. Well! I am going try. Joanie

  12. Diane says:

    what size jars and where can you buy them?

  13. nnicole says:

    My boyfriend is at sea and i can only send him one care package next month. I dont want him to open the brownies gift until his birthday in february. Would they last thay long?

  14. Dre says:

    Can you use batter that is made from scratch instead of the box? Will it work the same?

  15. ATesia says:

    Since these are not canned but just left to seal, how can I be sure that the food is still safe to eat?

  16. Dawna says:

    Hi: Love this idea and going to be making several different kinds to ship to my daughter at college. I have a silly question, what is the magnetic thingy you used and where do I find one? Would be very handy for grabbing the hot lids. Thank you!

  17. Jennifer says:

    hello :) this is my first time canning something. seems simple enough, the way you describe it. i just wanna know if “boiling the lids” also means boiling the rings too or just the lid/disc part. anyway, great idea and thank you for sharing it. don’t know why i didn’t think of it myself…must be the chocolate on the brain, gotta make some and cure that ;)

  18. Cindy says:

    This is such a fun, terrific idea! I made these for a birthday party and put frosting in a ziplock bag and some candies in another (tied with the raffia) and let the guest decorate their own special brownie before they gobbled it down! It was a HIT! Thanks sooo much for great idea! I love mason jars!!

  19. Linda says:

    I just did this for my daughter who is in the Navy – and for her roommates. They turned out wonderful. So excited to send them. Thank you so much!

    • Becky says:

      I was just wondering if you sent these to your daughter when she was deployed and if there was any issues with the disposal of the glass jars?

  20. helem says:

    I love this! I used to make these for my boyfriend when he was deployed in Afghanistan. He said they always arrived fresh. Now I make them for my coworkers all the time (they were the original guinea pigs lol). Best idea ever! Highly recommend it, especially for anyone sending their military men a sweet treat!

  21. Christine says:

    I’ve made these before. They are very good with chocolate chips in them too. You can get 4 oz canning jars from Walmart to make snack size brownies. I tested my brownies on my sisters and they raved about them. The only thing you need to be cautious about is making sure you hear the popping sound as the lid seals to the jar. After the jars are cooled, press down on the lid. If it has any movement downward, the lid didn’t seal properly and you’ll need to eat that brownie within a few days.


  22. Gioia says:

    I loved all the comments as I could not see the need at first for a canned brownie…lovely. AND, great idea about filling it with butter that you all made! I will use that idea. Thanks!

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  24. maggie says:

    I’ve made these using the half pint jelly jars to save on cost. Those squatty jars are cute but not for the price. I search thrift stores and yard sales for mason jars and find plenty for 25 cents to 50 cents a piece. Do not use marshmallows, they melt on the hot brownie and go bad really fast unless you eat them in a day or two. Just do the plain brownie and you’ll be OK. I have added chocolate chips and nuts and had no problems doing that. Box mix or home made both work great.

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