I started with the following recipe from simplyrecipes.com
Boston Brown Bread
Do your best to find the rye flour. It adds a lot to the flavor of the finished bread.
INGREDIENTS
- Butter for greasing loaf pans or coffee cans
- 1/2 cup (heaping) all-purpose flour
- 1/2 cup (heaping) rye flour
- 1/2 cup (heaping) finely ground corn meal (must be finely ground)
- 1/2 teaspoon baking powder
- 1/2 teaspoon baking soda
- 1/2 teaspoon salt
- 1/2 teaspoon allspice
- 1/2 cup molasses (any kind)
- 1 cup buttermilk
- 1 teaspoon vanilla extract (optional)
- 1/2 cup raisins (optional)
- One metal 6-inch tall by 4-inch diameter coffee can, or a 4x8 loaf pan
METHOD
1 You can either make this in the oven or the stovetop, and you can either make this with a loaf pan or a metal coffee can. If you are using the oven method, preheat the oven to 325° and bring a large pot of water to a boil. If you are using the stovetop method, set the steamer rack inside a tall stockpot and fill the pot with enough water to come 1/3 of the way up the sides of your coffee can. Turn the burner on to medium as you work.
2 Grease a coffee can or small loaf pan with butter. In a large bowl, mix the all-purpose flour, rye flour, corn meal, baking powder and soda, salt and allspice. Add the raisins if using.
3 In another bowl, mix together the buttermilk and vanilla extract if using. Whisk in the molasses. Pour the wet ingredients into the dry and stir well with a spoon.
4 Pour the batter into the coffee can or loaf pan taking care that the batter not reach higher than 2/3 up the sides of the container.
5 Cover the loaf pan or coffee can tightly with foil. If you are using the stovetop method, set the can in the pot, cover and turn the heat to high. If you are using the oven method, find a high-sided roasting pan that can hold the coffee can or loaf pan. Pour the boiling water into the roasting pan until it reaches one third up the side of the coffee can or loaf pan. Put the roasting pan into the oven. Steam the bread for at least 2 hours and 15 minutes. Check to see if the bread is done by inserting a toothpick into it. If the toothpick comes out clean, you're ready. If not, recover the pan and cook for up to another 45 minutes.
6 Remove from the oven and let cool for 10 minutes before putting on a rack. Let the bread cool for 1 hour before turning out of the container.
7 Slice and eat plain, or toast in a little butter in a frying pan.
Yield: Serves 4-6.
Here's what I did...
I began my "subversive" bread canning project by heating my wide mouth pint canning jars in the oven at 250 degrees for 20 minutes. I put enough water into my canner (or a large stockpot with a lid, used my canner because it's the only pot I have big enough) to cover the jars to about 1/3 of the way up the sides of the jars. I turned the heat on medium to get it going while I began mixing my batter.
I sprayed the insides of the jars with cooking spray (could have buttered them, but the spray was easier)
Next, I gathered my ingredients... I multiplied the original recipe by 4x so I could fill 8 pint canning jars.
I mixed all my dry ingredients in one large mixing bowl...
Then mixed all my liquid ingredients in another bowl (I chose NOT to add raisins)
I mixed the liquid ingredients into the dry ingredients
I filled each of the greased jars about 2/3 full of the bread batter (allowing space for the bread to rise)
I took great care to wipe the jar rims to remove any excess batter and any oil from the cooking spray...
TIP: a little vinegar on the cloth helps to remove grease and oil.
After simmering my lids in boiling water, I tightened the lids onto the jars to a fingertip tightness.
I placed the jars of bread batter into the simmering water in the big pot (canner)
I placed the lid onto the canner loosely (don't tighten it down) and kept the water at a low boil (you might need to adjust the heat occasionally, but keep it at a low boil, this is a steamed bread). I steamed my bread for 2 hours and 15 minutes.
After steaming, I removed the jars of bread using my jar lifter, and set them on a folded dish towel on the counter to cool, and to seal... didn't take long before I began hearing that PING of the jars sealing.
Next morning, I HAD to test the delicious looking (and smelling) bread. I popped open a jar...
I ran a butter knife between the inside of the jar and the bread...
... and it slid right out onto the plate... looking very yummy and cute... a miniature loaf of Boston Brown Bread.
I sliced it up...
...and spread it with some real butter... and enjoyed it with my morning coffee! Delicious!
*As I previously stated, this is NOT an approved canning method. I sterilize EVERYTHING and take great care to assure I use the cleanest utensils, jars, lids, bowls, pots and pans I possibly can. I have eaten "canned cakes and breads" up to a year or more after "canning" with delicious, moist results... I cannot stress enough that this is NOT an approved method... I choose to do it because I feel I use AT LEAST as clean and sterile methods as commercial companies (probably more so) and I'm a bit of a Rebel Granny... if you have ANY doubts... don't do it!
!
is pretty big. When my kids were home (especially my son as a teenager who could eat a whole cake and drink a gallon of milk in one sitting... I kid you not, he's done it and stayed skinny as a rail the little stinker!) I had no problem getting a cake eaten before it went stale. Now with just DH and myself and the kids a few hours away so they don't drop by often, if we get a hankering for some homemade pound cake and bake one, a lot of the time half the cake goes to waste before we can eat it all. Canning in 
divides a full sized pound cake into 7 or 8 jars, making mini-cakes for us to enjoy when we want... a box of brownie mix will fill about 4 jars.
because they have straight sides, it would be pretty much impossible to get the cake out of a small mouth jar** I could have greased the inside of the jars with shortening or butter instead but cooking spray is easier and easy is a good thing sometimes. **DON'T flour the jars like you would a pan, it just doesn't work with this baking/canning combo.**
and slid them into my preheated 325 degree oven. I set the timer for an hour and a half, but checked on them after about an hour. They're done when a knife inserted into the center of the cake comes out clean. This batch of little cakes was done in about an hour and 15 minutes.
and rims to a boil in water and left them simmering so they'd stay hot until needed.
and trimmed it down to the edge of the rim. **There's no need to be concerned about headspace with cakes**
thingy (a FANTASTIC gadget for getting hot lids out of hot water). I gave the lid a little shake to remove as much water as possible, then I tightened them onto the jars.
