Vegan Baking: Converting a Butter Cake and a Cookie, Step by Step

Most butter cakes and drop cookies contain three animal ingredients: butter, eggs and milk. Each has its own vegan replacement, and the guides cover them one at a time. The harder part is converting a whole recipe, because the swaps interact: plant butter changes how much liquid the batter can take, the egg replacement decides whether the cake rises, and the milk choice affects browning. Below, two common recipes are converted line by line, with the reason for each change. The chemistry of why eggs are hard to replace is in the egg science article; this piece is about applying it.

The starting recipe: a two-egg butter cake

A typical creamed yellow cake for a 9 × 13-inch pan: 2¼ cups (270 g) all-purpose flour, 2½ teaspoons baking powder, ½ teaspoon salt, ¾ cup (170 g) unsalted butter, 1½ cups (297 g) sugar, 2 large eggs, 1 cup (227 g) whole milk and 2 teaspoons vanilla. Gram weights follow King Arthur Baking’s ingredient chart.

Two eggs is a good candidate. The eggs weigh about 100 g against 270 g of flour, so flour carries most of the structure and the eggs mainly add lift, emulsion and moisture. A recipe with four or more eggs, or one leavened by beaten whites, is a different problem; start from an egg-free recipe instead.

The conversion, line by line

Original	Vegan version	Adjustment
¾ cup unsalted butter	¾ cup plant butter sticks	If the sticks are salted, cut the recipe’s salt to ⅛ tsp
2 large eggs	6 tbsp aquafaba	Beat in gradually, like eggs
1 cup whole milk	1 cup unsweetened soy milk	None
1½ cups sugar	1½ cups sugar	Choose beet or organic cane sugar if bone char matters
Flour, baking powder, vanilla	Unchanged	None

Butter. Stick-style plant butter is made to match butter’s fat and water, so it creams with sugar the same way and goes in at the same volume; see the butter guide. Most brands are salted. The guide’s rule for salted butter is about ½ teaspoon less salt per cup, which works out to roughly ⅜ teaspoon for ¾ cup, so the recipe’s ½ teaspoon drops to a pinch. If only refined coconut oil is on hand, use ⅞ of the volume: ¾ cup × ⅞ is about ⅔ cup. Keep it solid for creaming and add a tablespoon or two of soy milk, since coconut oil has none of butter’s water.

Eggs. In this cake the eggs’ main job is lift, so the replacement should be the one that traps air. Aquafaba at 3 tablespoons per egg is the ratio in the egg substitute guide; King Arthur allows up to ¼ cup per egg, and in its muffin comparison aquafaba came closest to the original. Flax gel would bind the crumb but add no air, giving a denser, moister cake. For a lighter crumb, hold back the aquafaba, whip it to soft peaks and fold it in last.

Milk. Unsweetened soy milk goes in cup for cup; the milk guide rates it the best-behaved plant milk in baking. Almond milk also works but the top browns less, so allow 2 to 3 extra minutes. Avoid vanilla-flavored or sweetened cartons, which add sugar and flavor the recipe did not plan for.

Sugar. Granulated sugar is plant-derived, but some cane sugar is whitened through bone char. A 2007 Vegetarian Resource Group report states that bone char is never used for beet sugar and that certified organic sugar is always bone char-free. Labels rarely say which source a sugar comes from, so strict vegans buy organic or labeled beet sugar.

Mixing and baking the converted cake

1. Cream the plant butter and sugar until pale, as in the original. If the mixture looks greasy rather than fluffy, the fat is too warm; chill the bowl for 10 minutes and beat again.
2. Add the aquafaba a tablespoon or two at a time, beating after each addition. Adding it all at once gives the creamed fat more liquid than it can absorb at one time, and the mixture can look curdled.
3. Alternate the dry ingredients and soy milk, starting and ending with dry, and stop mixing as soon as the flour disappears.
4. Bake at the original temperature and test the middle with a skewer rather than trusting the time. The aquafaba crumb is fragile when hot, so cool it in the pan completely before turning it out.

For frosting, plant butter sticks cream into buttercream directly. Half plant butter and half vegetable shortening holds piped shapes better on a warm day.

The cookie version: a classic chocolate chip

A standard chocolate chip cookie dough uses 1 cup butter, ¾ cup each white and brown sugar, 2 eggs, 2¼ cups flour, baking soda, salt and 2 cups chocolate chips. The eggs here mainly bind, and cookies tolerate density, so the conversion changes:

• Butter: 1 cup plant butter sticks. With coconut oil instead, use ⅞ cup and chill the dough for 30 minutes before scooping, or the cookies spread fast.
• Eggs: 2 flax eggs, made from 2 tablespoons ground flaxseed and 6 tablespoons water, rested 5 to 10 minutes until thick. Flax suits cookies because binding is the job; expect a slightly chewier, less puffy cookie and fine brown flecks.
• Chocolate: semisweet and dark chips can contain milk fat or milk solids. Read the ingredient list, not just the front label.
• Brown sugar: made from cane sugar and molasses, so the same bone-char question applies; organic brown sugar avoids it. In a pinch, the brown sugar guide rebuilds it from white sugar and molasses.

Common mistakes

• Using tub margarine or spread. It carries more water than stick plant butter, so the cake turns gummy and the cookies run thin.
• Choosing flax for a cake that needs to rise. The gel binds but holds no air, and a light layer cake comes out dense and flat-topped.
• Leaving the salt alone with salted plant butter. The cake tastes noticeably salty, because the recipe was balanced for unsalted butter.
• Trusting “plant-based” on the front of the package. Some plant butters include buttermilk or whey, and many dark chocolates include milk; check the ingredient list or an allergen statement.
• Pulling the cake at the original time without testing. With less protein to set it, an underbaked middle sinks as it cools.
• Converting a recipe built on eggs. Sponge, chiffon and custard pies lose their structure when the eggs go; see the egg science article for why.