Which Egg Substitute for Brownie Mix Still Gives You Fudgy Brownies?

Clear Answer

Plain Greek yogurt is the best swap: use 1/4 cup for each egg the box calls for, and the brownies come out dense and fudgy with no off flavor. Unsweetened applesauce (1/4 cup per egg) and mayonnaise (3 tablespoons per egg) are close runners-up. Skip aquafaba and flax if fudgy is the goal, since both lean cakey or gummy.

Boxed mixes are forgiving because the sugar, fat, and chocolate are already balanced. The egg is only doing a few small jobs, and the right substitute covers them without you changing anything else.

What does the egg actually do in a brownie mix?

In a box mix, the egg adds moisture, a little fat (from the yolk), and protein that sets as it bakes. That protein is what holds the square together when you cut it. The egg white also traps some air, which is why more eggs push brownies toward cake.

Fudgy brownies need less lift and more fat and moisture, so the substitute does not have to whip or rise. It should be wet, a bit fatty, and ideally carry some protein, which is what yogurt and mayonnaise bring.

Most boxes call for one or two eggs, plus oil and water. A large egg is about 50 grams (handy if you bake by weight), or a little under 1/4 cup once cracked. That is where the 1/4 cup rule for most swaps comes from.

Which substitutes work best, ranked

America's Test Kitchen tested seven egg replacements in a one-egg boxed brownie mix (Ghirardelli Chocolate Supreme). Their results are a useful starting point.

Two others come up often but were not in that test: a flax egg (1 tablespoon ground flaxseed plus 3 tablespoons water, rested 5 minutes) and commercial powdered egg replacer. Both bind, but flax tends to make brownies a bit gummy and nutty, and powdered replacers vary by brand. They are fine in a pinch, just not the first pick for fudge. Before trusting any other pantry swap in a recipe you care about, bake one test batch first.

Why Greek yogurt wins

Greek yogurt is thick, so it adds moisture without thinning the batter. It also has real protein (around 10 grams per 1/2 cup in plain 2% versions), which sets in the oven much like egg does. The slight tang disappears behind the chocolate.

Use plain, not vanilla or fruit flavored. Sweetened yogurt pushes an already sweet mix over the edge. Full-fat or 2% is better than nonfat, because the fat helps with that chewy, fudgy bite.

If you only have regular (not Greek) yogurt, it works, but it is thinner. Use 1/4 cup and cut the water on the box by about 1 tablespoon so the batter stays thick.

How to swap eggs in a box mix, step by step

This works for standard 18 to 20 ounce boxes from Betty Crocker, Duncan Hines, Pillsbury, Ghirardelli, and store brands.

1. Heat the oven to the temperature on the box, usually 325°F to 350°F. If you use a glass or dark pan, drop it 25°F, since those pans run hot at the edges.
2. Grease the pan, or line it with parchment with an overhang so you can lift the slab out later.
3. Stir the dry mix, the oil, and the water called for on the box in a bowl.
4. Add your substitute: 1/4 cup Greek yogurt, 1/4 cup applesauce, or 3 tablespoons mayonnaise for each egg listed.
5. Stir just until no dry streaks remain, about 50 strokes. Overmixing works in air and toughens the crumb.
6. Spread into the pan and bake for the time on the box. Start checking 3 to 5 minutes early, especially if your oven runs hot.
7. Pull the pan when a toothpick poked in 2 inches from the edge comes out with moist crumbs, not wet batter and not clean.
8. Cool completely, at least 1 hour, before cutting.

Eggless brownies are softer while warm and firm up as they cool. Cut them hot and they look underbaked even when they are not.

What if the box calls for two or three eggs?

Scale the substitute one for one: 1/2 cup Greek yogurt for two eggs, 3/4 cup for three. Mayonnaise scales the same way (6 tablespoons for two eggs).

Once you replace two or more eggs, the brownies lean softer and a bit less structured. A few changes help:

• Mix substitutes. For a two-egg box, try 1/4 cup Greek yogurt plus 3 tablespoons mayonnaise. You get protein from one and fat from the other.
• Cut back the water by 1 to 2 tablespoons. Applesauce and banana carry a lot of water, and reducing the box's water keeps the batter thick.
• Bake 2 to 4 minutes longer and lean on the toothpick test rather than the clock.

Many "fudgy" box versions (Duncan Hines Chewy Fudge, Ghirardelli Double Chocolate) call for one egg because they are designed to be dense. Those are the easiest to swap and give the best results.

Can you use mayonnaise without tasting it?

Yes. Mayonnaise works instead of eggs in brownies because it is mostly oil and egg yolk with a bit of vinegar, so you are partly putting the egg back in. Three tablespoons in a full pan of chocolate is undetectable. A full 1/4 cup tends to read as greasy, so stick to 3 tablespoons per egg.

Note that regular mayo contains egg, so it does not help with an egg allergy or a vegan bake. For those, use a vegan mayo at the same amount, or switch to applesauce or a dairy-free thick yogurt.

Miracle Whip is not the same thing. It has added sugar and spices and less fat. Use real mayonnaise.

Which swaps work for vegan or egg-allergy brownies?

Check the box first. Many standard mixes contain milk or are made on shared lines with eggs, so read the allergen statement if the allergy is serious. Some brands, including several store brands and Duncan Hines Chewy Fudge, have historically been "accidentally vegan," but formulas change, so verify each time you buy.

For egg-free and dairy-free results, your best options are:

• Unsweetened applesauce, 1/4 cup per egg. The most reliable vegan swap for fudgy texture. Use the plain kind, not cinnamon.
• Vegan mayonnaise, 3 tablespoons per egg. Rich and moist, very close to regular mayo.
• Thick plant yogurt, 1/4 cup per egg. Coconut or almond yogurt labeled "Greek style" works best. Thin ones need less box water.
• Aquafaba, 3 to 4 tablespoons per egg. Works, but expect a lighter, cakier square.

Gretchen's Vegan Bakery, a vegan baking channel, walks through its own egg replacement for box mix in a short video if you want a second method to compare.

Why did my eggless brownies come out gummy or crumbly?

Most problems trace back to moisture or baking time rather than the substitute itself.

A short chill helps every eggless batch. After the brownies cool to room temperature, refrigerate them for 30 minutes and then cut with a knife wiped clean between slices. You get sharp edges and a denser, fudgier bite.

How should you store eggless brownies?

Store them covered at room temperature for up to 3 days, the same as regular boxed brownies and much like storing bread on the counter. Yogurt or mayo versions are cooked through, and the high sugar content keeps them stable on the counter for that window.

If your kitchen is warm or humid, move them to the fridge, where they keep about a week. Cold brownies are even fudgier, which many people prefer anyway.

For longer storage, wrap the cut squares individually in plastic and freeze for up to 3 months. Thaw on the counter for about 30 minutes.

A few extra tips for fudgier box brownies

These help whether you use eggs or not:

• Add 2 tablespoons of melted butter in place of 2 tablespoons of the oil for richer flavor. Melted coconut oil also stands in for the oil.
• Stir in 1/2 cup chocolate chips. They melt into pockets and make the texture feel denser.
• Use a metal 8x8 pan for thicker, fudgier brownies, or a 9x13 for thinner, chewier ones (the box gives times for both).
• Add 1 teaspoon of instant espresso powder to deepen the chocolate without tasting like coffee.
• Pull them slightly early. Brownies keep cooking from the heat of the pan for several minutes after they leave the oven.

Swapping eggs in a boxed brownie mix, start to finish

The right batter thickness is easier to judge by eye than by description, especially once the egg is gone. A vegan baker walks through a boxed mix.

How to Replace the Eggs in a Brownie Mix
By Gretchen's Vegan Bakery on YouTube. Their method may vary a little from ours. Watch on YouTube