15x10 Inch Pan Brownies

My go-to brownie pan is an 8-inch square, but a few months ago we were invited to a picnic so I made brownies in a 15x10 inch jelly roll pan. Maybe it was the dark brown sugar & espresso, or maybe it was just that I'd cut the brownies large and wrapped them individually. Whatever the case, I've never seen a pan of brownies disappear that quickly.

15x10 Inch Pan Brownies vs 13x9 inch Pan Brownies

One reason I used the jelly roll pan rather than the usual 13x9 inch was that I recently bought a 15x10 inch USA pan that's always on the counter. In the past, my old 15x10 inch pan was buried under piles of other pans and there'd be an avalanche of cookware whenever I went looking for it. This new one's always at arm's reach. So it was convenient, plus I wanted to see how thin the brownies would be and what the crust would be like when baked in a shallower pan. Here's a picture of the first batch. I splurged a and used Guittard's Bittersweet Wafers melted into the brownies and on the half of top. The bottom half has Ghirardelli's bittersweet chips.

Chocolate for 15x10 Inch Pan Brownies

We loved the version made with the melted Guittard wafers, but it was pretty expensive, so I made a second batch with melted Ghirardelli bittersweet chips and a third batch using melted chocolate bars from Aldi -- half dark chocolate 49% Choceur and half 85% Moser Roth. The melted Ghirardelli chip version was good, but the texture wasn't quite as smooth as the brownies made with baking wafers or melted bars. So if possible stick with bars. Also, don't leave out the extra 28 grams of unsweetened chocolate. It might seem insignificant, but it's part of the recipe. Any brand will do.

Coconut Oil and Flaky Salt for Greasing Pan

The best tip I've ever read on Twitter is this one: Grease brownie pans with coconut oil and sprinkle sea salt on the bottom so that you get a taste of salt in each bite. These brownies are thinner, so the salt bite is amplified and more noticeable but in a good way. It's an optional step, and only for people who like a little burst of salt.

Espresso Powder

Espresso powder is worth using as it really adds to the flavor. I like espresso, but am sensitive to caffeine so I use it anyway and eat the brownies before noon. If you don't have or don't want to use espresso powder, just leave it out.

1 Tablespoon of Vanilla

This may seem like a lot of vanilla for one brownie recipe, but remember it's a 15x10 inch pan with 2 ½ cups of sugar and 1 ⅓ cups of flour, so proportionately it's not that much.

Dark Brown Sugar in Brownies

The dark brown sugar (along with the espresso powder) makes these brownies special, so I recommend using dark over light. The dark brown sugar gets added to the melted chocolate mixture so it is mostly dissolved, while the granulated sugar is added later.

Large Batch Size

A 15x10 inch pan brownies should yield 24 decent size brownies suitable for wrapping individually. For a party, you could divide each of the brownies in half or into quarters and serve 48 wedges or 96 cubes give or take missing scraps and edge pieces. I like to trim the edges and bake them like biscotti.

Gluten-Free Large Batch Brownies

I've been doing a lot of gluten-free baking lately, so when I get a chance I'll test these with a 1:1 blend. There's no reason why it shouldn't work, but I'll report back after testing. I will also test in a 9 inch square pan, which is the size I use when halving recipes calling for a 15x10 inch or jelly roll pan.

Baking Time

Brownie baking times can be tricky. The recipe calls for 330F convection for 25 minutes, but say to check at 20. If you bake the brownies at 330F in a regular oven without convection, the brownies might take a little longer. You can't go wrong if you test the internal temperature with an instant read thermometer and target 200 degrees F.

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