When you get past the glitter and glam of holiday cutout cookies, what are you left with? Often, a rather insipidly sweet and undistinguished cookie.

Which is why I just say no to sugar-sprinkled stars, heavily iced reindeer, and anything – ANYTHING – draped in dragées.

Big Batch Brownies and Bars via @kingarthurflour

Instead, I like to gift my nearest and dearest with undistinguished-looking but absolutely delicious brownies and bars. Which means I turn to big batch brownies and bars: the surefire way to save time, money, and lots of colored icing-induced irritation.

What's the best way to make lots and lots of brownies and bars all at once?

First, do some easy math.

Find a recipe that fills a 9" x 13" pan, double it, and bake it in a half-sheet pan (13" x 18"), right?

Wrong. And here's why –

While the classic dimensions of a half-sheet pan are 13" x 18" (double the size of a 9" x 13" pan), in reality most half-sheet pans measure about 12" x 17", inside dimensions.

Plus, a half-sheet pan is only 1" deep, while a typical 9" x 13" pan is 2" deep. So a half-sheet pan actually offers a lot less baking real estate – both horizontally, and vertically – than you might think.

Doubling that high-rising brownie recipe and sticking it in a half-sheet pan offers the potential – nay, the likelihood – of half-baked batter bubbling over the 1" sides of the pan onto the oven floor. NOT a pretty picture.

But don't give up on your handy half-sheet. You can still start with your favorite 9" x 13" bar recipe; but instead of doubling it for the larger pan, increase all of the ingredients in your 9" x 13" recipe by 50%.

This is most easily done with a scale. And a tiny bit of math.

Big Batch Brownies and Bars via @kingarthurflour

Choose your recipe.

I've decided on a simple stir-together one-bowl brownie recipe, Quick and Easy Fudge Brownies.

The recipe calls for a 9" x 13" pan. Check.

Next, increase all of the ingredient amounts by 50%.

Easiest math? Metric. I consult the gram weights in our recipe, and from there, it's simple to increase everything by half.

But what about the eggs, you ask. How did 3 large eggs, increased by 50%, become 224g eggs?

Serendipitously, a typical large egg weighs about 50g. So 3 eggs weigh 150g. Times 1 1/2 = 225g eggs. (So OK, I came up with 224g; it's a boring story involving decimal points and rounding...)

Big Batch Brownies and Bars via @kingarthurflour

Then, mix and bake your big batch brownies.

Make the batter. Spread it in the pan. Bake.

I've discovered that using this method doesn't change the baking time, though you'll probably want to stick with the shorter time if the recipe gives a range. And while it results in slightly thinner bars, the difference isn't appreciable.

Big Batch Brownies and Bars via @kingarthurflour

Finally, cool and cut into squares.

You'll get anywhere from 4 dozen largish (2") squares to 88 smaller (1 1/2") squares.

I prefer smaller squares for gift-giving. Keeping things small allows you to offer a wider array of treats on one plate. Plus, c'mon, everyone you know is trying to keep weight gain in check over the next few weeks – give your friends a hand by keeping portion sizes small.

One final note: what if your recipe calls for an 8" x 8" pan, or 9" x 9"?

Back to the chalkboard. The interior surface of a half-sheet pan measures 204 square inches (12" x 17"). Increasing a 9" x 13" pan by 50% = 175 1/2". Since we know 175 1/2" is the "sweet spot" – bars fill the pan nicely, without overflowing – that's the number we're going for with other size pans.

Doubling a 9" x 9" pan recipe = 162", about 8% less than 175 1/2". Seems like it should work.

Tripling an 8" x 8" pan recipe = 192", about 9% more than 175 1/2". You MIGHT be risking too much batter (overflow), but give it a try. Put a pan underneath to catch any potential drips, and you'll be good to go.

Big Batch Brownies and Bars via @kingarthurflour

Good. To go – right onto your holiday gift plate.

Now go forth and bake!

What kinds of baked treats do you like to gift during the holiday season? We'd love to hear about some of your favorite recipes in the comments below! 

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About PJ Hamel

PJ Hamel grew up in New England, graduated from Brown University, and was an award-winning Maine journalist (favorite topics: sports and food) before joining King Arthur Flour in 1990. Hired to write the newly launched Baker’s Catalogue, PJ became the small but growing company’s sixth employee.PJ wa...
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