What cornstarch does in cookies—and what it does not do

Cornstarch is a texture ingredient

Sally’s soft chocolate-chip cookies use 2 teaspoons of cornstarch alongside 250 g all-purpose flour, with baking soda and a required chill. The source attributes a softer, thicker result to that complete formula. These quantities identify one example; they are not a ratio to add to every cookie recipe.

Cornstarch is not baking soda or baking powder. It does not provide their chemical leavening function. Adding it is also not the same as correcting a known omission of flour.

Read how the recipe uses it

Look at whether the starch is included alongside flour, replaces part of another dry ingredient, or appears in a special flour blend. Then follow the stated measurement and mixing step. These arrangements cannot be merged into a universal teaspoon-per-cup rule.

If your goal is a tender cookie, choose a recipe developed for that texture. If your existing cookies spread unexpectedly, investigate measurement, butter handling, pan setup, and chilling before adding an ingredient the recipe never called for.

Check the package name

Regional terminology can be confusing. Doves Farm’s US-cup reference explicitly labels its “cornflour” as corn starch. Read your package’s ingredient description and the recipe’s regional context. Cornmeal is a different ingredient; the shared word “corn” does not establish a substitute.

A useful comparison record

Write the original flour and starch weights, the exact ingredient you used, and whether all other ingredients remained the same. Compare cookies after equal cooling times.

If you are out of cornstarch, look for an alternative supplied by the recipe author. A starch substitute suitable for thickening a sauce does not automatically preserve a cookie’s spread and texture.