I would cut the time by a third and I really like the jars! I save Bonne Maman jars for storing my homemade caramel and chocolate sauces and cherish them!

I save Bonne Maman jars

Bumble, thank goodness I'm not the only one! I have an entire shelf of them. I can't believe I alone eat that much jam!

I am using some of those jars with lids to store crafts bits and am replacing the delicate votive cups in a hanging candelabra. They are pretty sturdy and I think they would work well. Because heat comes in from the outside to the center, I would think narrower could be less baking time. Glass is also a good conductor of heat -- you tend to bake at a slightly lower temp with glass. I'd keep an eye on them starting at 35-40 minutes. I hope you will report back -- I might have to try them too!

Bonus points for buying the unusual Bonne Maman jams, preserves, whatnot for the unusual jar shape and color of lid ;-)

Bonne Maman is the best jam at a reasonable price. I love their Blackberry. The jars are perfect for decanting large containers of olives or capers. They are quite sturdy and the lids are good.

So crazily OT, but just this morning I was marveling at how amazing their jam is compared to a pricier jar of Belgian jam, which I bought for the jar.

What a clever idea and I hope they work out for you. I'd like to try something like that. I have about a dozen Le Fermier yogurt jars and another dozen or so Oui and I've been saving ideas on how to re-use them. When I have luncheons I make individual floral arrangements and either put one by each place setting or line them up in the center of the table. And then of course everyone takes one home when they leave. One Christmas I used them for votive candles and glued holly leaves and winterberries around the base. Le Fermier comes in glass or blue terracotta pots.

http://www.lafermiere.us/our-products/

My mom made homemade raspberry jam when I was a kid, and until I found Bonne Maman, none of the brands that I'd tried measured up. I'm a fan, too, though I only keep 4 or 5 of the jars on hand. If I kept every one, I'd have no room for anything else. For jam fans, I highly recommend checking out the Small Batch Jam Company (found them at a craft fair last year). Their ginger pear butter was amazing. So was the blackberry pinot thyme jam.

Sorry, no advice on the original question.

"Because heat comes in from the outside to the center, I would think narrower could be less baking time."

That makes sense, lacatx.

Jam jars can be really nice. I have used some as votive holders but just wasn't sure about the oven.

graywings, FWIW I found a recipe for pots de creme in jam jars. Instructions say to put 3/4 cup of the chocolate cream mixture into each jar, or about 1/2" from the top. Bake 300 for 40-45 minutes.

Thanks for the Fine Cooking link, Chloebud. It sounds as though the pot de creme does not expand during baking. So I can fill the Oui jars with it.

Chloe, that is the exact shape the chocolate pots de cremes I buy from Miette in SF are.

Zalco, those are really nice!

I look forward to a report. Meanwhile -- I have to make a trip to Whole Foods to try the La Fermiere. I'm such a sucker for the little blue pots -- at least the first half dozen to a dozen or so. LOL For many years, I had the working glasses because they looked like the jelly jars. Other than Welch's grape jelly for the kids PB&J years ago, I don't buy much jam, but when I do, that is one I look for.

I see a Whole Foods trip coming up!

Thank you all for the advice. The Oui jars worked out beautifully. I used the Fine Cooking tip of an instant read thermometer to check for doneness. They came to 150 degrees in 38 minutes and were pretty darn perfect, if I do say so myself. I helped it along by filling the pan with 160 degree water from my teapot.

I really appreciate when my intuition lines up with with known outcomes so when I said cut the time by a third that would be 38 minutes. Thank you for reporting back and I am so glad they turned out great! And I am more confidant in my gut feelings too.

Nicely done!

Bumblebees -- you get the prize. I was thinking more in the 1/4 range, but the warm water to start helps. But most importantly, the look great, the jars work and I'm assuming they tasted great!

Lascatx, I know that came across as tooting my own horn and I didn't mean that in any way whatsoever. It's just nice when you have a gut feeling and it turns out to be right!