Whole and ancient grains are still on "the trend list" for 2016 and they are unlikely to fall off of it anytime soon.
While it’s definitely tricky to transform baked goods made with all-purpose wheat flour into ones make entirely with another flour (there are no tried and true formulas or silver bullets for doing so), it's not so tricky to introduce new flours into your baking in small measures.
You can experiment by replacing some of the all-purpose flour in a recipe with the same amount of another (more interesting!) flour that will add texture, flavor, nutrients, and perhaps even a little color to your cakes and cookies.
If you start conservatively, replacing only 15 to 20% of the flour in a tried and true recipe (you should know the recipe works in the first place), you are unlikely to have grand failures or major ingredient waste. If your first result tastes great, you can stop there or continue the experiment by replacing a little more of the flour. I’ve done this endlessly over the years.
The notes below reflect my experience with several grain flours, including the pseudo-grain buckwheat flour, as well as chestnut flour (but not other nut flours). Use them as rough guidelines—it’s still best to start with one small change at a time in a recipe that you know well, lest your efforts end in the trash. The goal is to enjoy the journey of experimentation and eat the results along the way!
You may be able to replace up to 50% of the all-purpose flour with whole wheat, kamut, or spelt flour—all of which are varieties of wheat and contain gluten. (The chocolate chip cookies on page 133 of my book Chewy Gooey Crispy Crunchy use 100% whole wheat pastry flour instead of all-purpose, and this is probably good for oatmeal cookies and definitely for my ginger cookies, too). I haven’t tried barley or rye but see no reason why you couldn’t.
You may be able to replace up to 35% of the all-purpose flour with a gluten-free grain flour such as corn (flour, not meal), oat, sorghum, brown rice, teff, the pseudo-grain buckwheat flour, or chestnut flour.
You may be able to replace up to 50% of the all-purpose flour with a gluten-free grain flour such as corn flour or oat flour, or with the pseudo grain buckwheat flour or chestnut flour.
You may be able to replace up to 25% of the all-purpose flour with whole wheat, kamut, or spelt flour. (The Kamut Pound Cake in Pure Dessert uses 1 cup sifted cake flour and 1/3 cup plus 1 tablespoon whole-grain kamut flour.) I have not tried rye or barley yet, but see no reason why not.
You may be able to replace up to 33% of the all-purpose flour with a gluten-free grain flour such as brown rice, corn, oat, sorghum, teff, or chestnut flour. Buckwheat flour may work also, but should be stirred in at the end to avoid becoming gluey from too much beating.
In some sponge cakes (especially génoise and chiffon cakes) you can substitute a gluten-free grain flour or buckwheat or chestnut flour for all of the all-purpose flour in the recipe! That being said, you can also replace just a portion of the flour in these recipes. (See Flavor Flours for several sponge and chiffon cakes made with non-wheat flours.)
As I write, I realize that I have never substituted any whole-grain wheat flour for all-purpose flour in a sponge cake! Anyone?
You can often substitute a gluten-free grain flour or buckwheat flour for all or any part of the all-purpose flour. You may have to adjust the liquid a bit to get the right texture.
Some of my favorite flours for pancakes and waffles are brown rice, oat, chestnut, sorghum, and buckwheat. Buckwheat has an assertive flavor: If you are not used to it, start by substituting it for 50% of the all-purpose flour and working up from there.
For recipes that combine whole grains and non-wheat flours with all-purpose wheat flour, see Pure Dessert (Artisan, 2007). For gluten-free recipes made with whole and ancient grains and nut flours, see Flavor Flours (Artisan 2014).