I don't think I've ever made french toast from a recipe, but I've made french toast with more or less the same basic batter and all kinds of bread and it always works fine.

I just make my regular french toast batter and use grainy bread. It comes out just fine. It's a slightly different texture, a little firmer, but I like it. It may have to soak a bit longer, but other than that I don't see why you can't swap it out in any french toast recipe.

I think the best french toast I've ever made was from a vegan cookbook. I used whole grain bread since that's usually what I have on hand. It calls for chickpea flour, which gives the french toast an awesome coating and flavor. The recipe also calls for a few different kinds of nut milks/creamer but I just used all almond milk and had good results so don't be afraid to play around with the recipe. I'm pretty sure I added some cinnamon and vanilla extract to the batter as well.
http://www.theppk.com/2008/10/fronch-toast/

I don't change anything about my french toast recipe, whether I use challah or whole grain bread (like I did yesterday). I just make sure that darker breads absorb more of the liquid before frying to soften them up a bit.

Like the others, I don't alter my recipe when using whole grain/whole wheat bread and instead just makes sure I get a good soaking of the egg/milk mixture before frying it up.

I had a whole grain french toast with a cornflake crust at a hotel once, it was really good, the heartiness of the whole grain paired really well with the cornflakes.

-Ruth

I soak mine for a while and then have it sit on a wax paper-lined cookie sheet before cooking. It gets all mushy inside!

Trader Joe's sells an excellent whole wheat raisin bread that makes for delicious french toast. I let it soak in a mixture of soymilk, egg, cinnamon, and a bit of maple syrup.

Just let it soak longer, maybe poke some extra holes with a fork. It will never be the same as French toast made with airy white bread, but it's still good.

Like others said, first off, I don't have a recipe. A recipe for french toast is like having a recipe for scrambled eggs.

But to alter it for a denser bread, there's really nothing to alter. Fluffy bread soaks up faster, so just let the bread sit in there for a bit longer and cook it. Done.

The best french toast my mom ever made used a hearty, crusty rye bread from a local bakery. She used a regular egg-and-milk soak and fried it in butter, and it was amazing. Just skip the extras, like cinnamon and vanilla, and use a super good quality bread. It'll have plenty of flavor on its own.

Agreed with all that the best French Toast is made with dense grainy breads. And for me, it must involve copious amounts of freshly grated nutmeg.

this is the best french toast i've ever had (and i've had a lot!) i bet it would be great with whole grain bread, and as others have mentioned before, i would soak it a little longer. http://www.foodnetwork.com/recipes/alton-brown/french-toast-recipe/index.html