Troubleshooting: Why Boxed Gluten-free Cake Mixes Can Behave So Differently
When I created my homemade cake mix, my goal was to keep the sugar lower and use a higher ratio of coconut flour than most brands. Coconut flour is incredibly absorbent, and it’s what gives so many of my recipes that tender, cake-like consistency.
As with all of the substitution ideas here, sometimes I’ll recommend a boxed grain-free cake mix as a substitute for ease, but those suggestions are not tested with each and every recipe. They are there to provide guidance if you’re ready to experiment, but the recipes are always best made as written.
The store-bought mixes worked well in muffins or breads when we tested Make It Easy and the other recipes using my cake mixes here, so I felt confident offering it as an option for the new cookies. But unfortunately most of them didn’t hold up when I got back into the kitchen and tested them.
They worked well where the batter is contained in a loaf pan or muffin tin, but after testing I realized cookies are a different story. Recently, when we swapped in 2 different boxed mix for cookies, the dough was runnier and the cookies spread far more than with my homemade blends.
Tune into this video if you want the full deep-dive science lesson, but here are the likely culprits:
1. Coconut Flour Ratio
My mix contains more coconut flour than most boxed mixes, which means it binds moisture better and sets faster in the oven. Simple Mills uses less coconut flour than mine, and I suspect they’ve also changed their coconut flour source in the last year because I’ve noticed their batters are way more runny than they were when we tested for Make It Easy two years ago. This is a sign that the coconut flour they’re sourcing isn’t absorbing liquid the way it used to, or that they changed the formula and increased their arrowroot and reduced their coconut flour. I reached out to the brand to see if there were any changes and didn’t receive a response.
2. Added Sugar Content
My mix starts with less sugar in the base, so I can control how much is added from recipe to recipe. Some recipes like Banana Bread don’t need as much sweetener in the cake mix because of the ripe bananas, while others- like a chocolate mug cake that has cacao powder need a little extra sweetness to balance it.
So when you add sweeteners for cookies, they’re mostly dry sugars like coconut or maple sugar. Simple Mills, and most other boxed mixes, have more sugar built into the mix itself, so when you add more, it can tip the balance. Sugar liquefies as it bakes, and more of it means more spread.
In a cake or muffin, the sides of the pan contain the batter, and the long bake time (45–60 minutes) allows the starches and proteins to firm up before gravity has much chance to pull the structure down.
In cookies, with no pan walls and a short 12–14 minute bake, the liquefied sugar has more opportunity to spread the dough outward before the flours and eggs have time to set.
If your starting mix already has more sugar (like many boxed mixes do), and you add even more for cookies, it tips the balance toward spreading fast.
3. Leavening Type: Baking Powder vs. Baking Soda
My mix uses baking powder (a blend of baking soda and cream of tarter) which gives a slower, steadier rise. This means the structure has more time to set before the leavening gases escape.
Simple Mills uses baking soda alone, which reacts immediately with any acid in the dough (maple sugar, coconut sugar, honey, etc.). In a loaf that bakes for an hour, the quick initial rise still has time to be reinforced as the heat sets the structure.
But in cookies, which bake quickly and are thin, that early rise can collapse before the flour structure is strong enough, contributing to spreading.
4. Compared to a Standard Gluten-Free Cake Mix
A typical gluten-free cake mix has more starch (rice, potato, tapioca) plus xanthan gum. That combo makes a much gummier, more elastic dough that can hold shape better in cookies, but with a very different texture than my recipes. Made as is, a gluten-free cake mix like King Arthur still spread too thin. We needed to add coconut flour to it to make it less gummy, but also hold it’s shape more.
Possible Fixes
I’ve updated the recipe with a note to add coconut flour when using boxed mixes, but here are a few other options to help you get the right texture. Remember, all boxed mixes are a little different, so you only need to choose one of these adjustments, not all of them.
Reduce the sugar - This helps across the board. Cut both the coconut sugar and maple sugar in half, and reduce the almond milk by half as well.
Add coconut flour to an already-mixed dough. If you’ve made the dough and it feels too runny:
Add 2 tablespoons at a time
Let it sit 5–10 minutes so the flour can hydrate fully
Continue adding in 2-tablespoon increments until the dough holds its shape
Chill the dough - refrigerate for 30–60 minutes before baking to slow spreading.
Reduce the eggs - My recipes with higher coconut flour need two eggs for structure, but if you’re using a mix with little or no coconut flour, one egg is often enough. Too many eggs in a lower-absorbency mix can make the dough looser and contribute to spreading.
Boxed mixes can absolutely work in many recipes, but their flour ratios, sugar content, and leavening agents make them behave differently, especially in cookies. With a few tweaks, you can get much closer to the results you’d see with my homemade mix.
I’ve updated the original recipe here with how to modify the 2 cake mixes we tested with. We made the recipe as written, but just added coconut flour and while the texture is still different from the original, they set up beautifully and were great!
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