For this test, I used Betty Crocker's Fudge brownie mix. Each box was $2.99.

The classic fudge mix calls for 1/2 a cup of oil, 2 tablespoons of water, and two eggs.

One 24-ounce jar of Mott's applesauce was $2.

Since applesauce works as a binder and an emulsifier, according to Business Insider's egg replacement chart, it should provide moisture and body to baked goods like brownies.

I had previously made oat cookies with applesauce, but I had never tried it in a box mix.

To replace the two eggs in the brownies, I used 100 grams of applesauce, which is just over a 1/3 cup.

I first mixed the applesauce with water and then added the oil, but it didn't seem to fully incorporate.

Since it wasn't fully emulsified, the applesauce mix seemed to separate a bit in the pan. After pouring it in, I saw some of the oil appearing in the corners.

I cooked each batch of brownies in this test at 350 degrees Fahrenheit for 35 minutes or more as needed.

At the 35-minute mark, the applesauce brownies still looked undercooked, so I left them in the oven for an additional 10 minutes.

Even then, the brownies still seemed a little undercooked when I cut them.

Despite being cooked for the appropriate time, the brownies seemed undercooked on the inside — maybe they could've benefited from staying in the oven a few extra minutes so the mix could solidify a bit more.

However, when it came to the taste, they were fudgy and rich and didn't have any apple taste.

One 16-ounce container of tofu was $2.99.

I used 160 grams to replace two eggs — just under a third of the pack — which added about 7 grams of protein to the brownies.

While I'm familiar with tofu from being a vegan in the past, I had never used it in baking, so I was intrigued by its potential.

The silken tofu was very soft, and it was a little challenging to drain the water from the container without the tofu also falling out.

I first mixed the tofu with the 2 tablespoons of water and then added the oil. The tofu seemed to emulsify a lot better than the applesauce.

At first, white clots of tofu were a little intimidating, but after mixing it more, they blended nicely.

The mix was thicker than the applesauce, but it was also smoother.

Out of the oven, the tofu brownie had a nice shiny layer on top.

It had also risen a lot more than the applesauce brownies and didn't look as oily.

Having risen a little more than the applesauce brownies, the tofu brownies had more of a cake-like texture and were a lot lighter.

They were a little crumbly — not dry — but I didn't mind it too much because of the nice lightness the brownie had.

Mayonnaise, which is made from eggs and oil, made sense as an egg replacement, although I wasn't very fond of the idea.

One 8-ounce jar of Hellmann's mayonnaise was $3.99, making this alternative the most expensive per serving.

While I can enjoy mayonnaise in savory dishes, the idea of using it for brownies was a little daunting. I wasn't looking forward to it, but I was open to having my mind changed.

I used 6 tablespoons of mayo to replace the two eggs.

I first mixed the mayonnaise with the water and then added the oil, and it seemed to emulsify really well.

Pouring it in the pan, the mix did not look as smooth as when I had used other egg alternatives. It was also the thickest, so I had to spread it out.

When I first checked on the brownies at the 35-minute mark, the mix was still completely liquid.

I let them cook until they solidified for an extra 30 minutes, 10 minutes at a time, and checked until they looked done.

When I pulled them out of the oven, oil was bubbling through the flat top.

The mayonnaise brownie was extremely oily and a little too chewy and hard.

I also thought it had a bit of a weird flavor, but that might have been more of a mental block on my part.

The chia seeds seemed expensive at $8.88 for a 2-pound bag, which was the only one I could find at the store.

Still, the large bag meant the cost per serving was actually lower than the mayonnaise.

I had used chia seeds in baking before, so I knew going in that it usually meant recipes turned out more crumbly than expected.

I first mixed 2 tablespoons of seeds with 6 tablespoons of water to make a "chia egg" — it took about five minutes for the mixture to settle in a gelatinous texture.

I then mixed it with water and then the oil.

Although you could still see the seeds, the mix itself was smooth and not too dry.

Although textured, the mix was still smooth and runny enough to cover the pan without me spreading it.

When I took them out of the oven, the brownies didn't seem to have any oil bubbling through and had a nice crispy edge and top.

With a nice crispy top and fudgy bottom, the chia brownies were my favorites by far. They were the perfect balance of rich and crunchy.

The chia seeds also added a fun crunch to the brownie, and I really enjoyed the texture.

Aquafaba, the liquid leftover from cooking chickpeas, is supposed to help with emulsifying, binding, and leavening, making it the most complete replacement, at least on paper.

One can of chickpeas was $1.25, making this the cheapest alternative. I used 6 tablespoons of the liquid to replace two eggs.

I had never used aquafaba, and while I had heard a lot of good things about it, I was a bit uncertain about how these would turn out.

Filtering out the liquid, I had to remove some chickpea skins from the aquafaba, which had a thick, watery texture, like watered-down egg whites.

I first mixed the aquafaba with water and then added the oil. While mixing it, the liquid became white and lighter. I was afraid of over-beating it, so I stopped once it felt like a liquid egg mixture.

While it emulsified well and the oil didn't seem to separate, the mixture was very runny, more than the other alternatives.

Given how thin the mixture was, I expected this brownie to be lighter than the rest, more cake-like than fudgy.

Out of the oven, the brownies looked unlike any of the others. They had a crispy layer on top and crispy edges, while the center appeared to have caved in.

While I wasn't sure what to expect from the look of them, the brownies themselves were delicious and fudgy.

The thin layer of crisp on top and the crunchy edges made for a perfect balance with the rich center.

Of the five alternatives, silken tofu, chia seeds, and aquafaba all worked well, and I could see myself using them again depending on what kind of brownie I wanted.

For a lighter, more cake-like brownie with added protein, I'd choose the silken tofu. If I wanted a decadent and rich chocolate experience, I'd choose the aquafaba.

For a perfectly balanced brownie with a nice crunch, I'd go for the chia seeds, which were my favorite of the five in this experiment.

On the value front, both the chia seeds — despite the high cost upfront — and the aquafaba offered the lowest cost per batch, and considering aquafaba usually gets discarded when using a can of chickpeas, this seemed like a creative way to use it.

Compared with the price of eggs — a dozen Grade-A large eggs cost an average of $4.95 in January — the chia seeds, aquafaba, and applesauce were all at least three times cheaper than using eggs in the recipe, while the tofu and mayo were just a little more expensive per serving.

Ultimately, the aquafaba and chia-seed brownies provide a pleasant alternative while also being significantly cheaper.