It all started with a challenge on IRC. Could a not-thoroughly-gross cookie be made with mushrooms in it? Taking an existing oatmeal cookie recipe as a base and assuming that sweet must be replaced with savory, I was able to concoct a reasonably edible thing that resembles a cookie and has mushrooms in it:

Click "read more" below for details.

Introduction

Cookies are, at their core, usually the following ingredients:

1. Flour. Something has to form the structure to hold the bubbles formed by the:
2. Baking powder (or soda). Add water and heat and you get bubbles held in place by the flour and the:
3. Eggs. Which add both additional proteins and emulsifiers to the equation, but all that water has to be held in check by:
4. Sugar. Which is both sweet and hydroscopic (it grabs some of the excess water). All this is pointless, however, unless we have a:
5. Payload. Sugar is sometimes payload enough, but usually there's raisins, other grains (oats, e.g.), chocolate, or some other payload.

In order to make a savory cookie instead of a sweet one, the big challenge is to figure out how to duplicate sugar's unique qualities without being sweet. Those properties?

1. Hydroscopic. We'll have to suck excess moisture out of the cookie batter somehow.
2. Abrasive. Sugar crystals rip into the various egg proteins as it's being whisked (and forming a solution with) the wet ingredients. Extra beating will be required if we don't use it.
3. Caramelizable. Add enough heat to sugar and it caramelizes, and caramel eventually cools to help form the crispy bottom. I forgot about this one in the initial formulation...

Ingredients

A typical oatmeal-raisin cookie has quite a bit of grain in it, and holds a payload that's about chopped mushroom size. I figured that was a good place to start. The ingredients, side-by-side with the original, are:

Procedure

A typical cookie procedure is to simply combine the dry ingredients (sugar is considered a wet ingredient for this process) in one bowl. Then the wet in a separate bowl (whisked vigorously until the sugar is fully dissolved), then mix the two together. With muffins or biscuits, you'd fold the ingredients. With cookies, it's not so important--mix away.

This process diverged a bit because of the immense amount of cheese and the extra mixing of the wetworks because of the lack of sugar. I started with the truly wet ingredients (except the milk, which was an afterthought), whisking vigorously with a metal whisk to really beat the eggs. I then added the cheese, continuing to beat the heck out of it and form a partial emulsion (the cheese wouldn't dissolve, but it would break up into small bits and egg was definitely sticking to it. The barley was semi-wet, so it came next. Then the dry goods (which had been whisked together in a separate bowl). Chopped mushrooms entered the party dead last.

When the batter came together, the flour wasn't integrating as it should (not enough moisture), so I slowly added milk until the consistency hit something reasonable. At this point, the batter smelled like a baking pizza--quite nice.

I then dished out rounds onto a waxpaper-covered cookie sheet, 8 per batch, in two batches. I then put a little grated cheddar on top and a sliced mushroom in the middle of each. Then into a 375 F (190 C) oven for 12 minutes and on to a cooling rig (cooling rack over aluminum foil).

Results

The final cookies looked like this:

They were reasonably tasty (reminded me of quiche filling), but had the following problems:

• Not crispy enough. I hadn't taken the caramelizability of sugar into account, so the cookies ended up a bit on the not-quite-hard-enough side. Normal cookies, if you grab them from a corner, will hold straight--mine drooped a bit.
• Too much cheese. I never though I'd say that, but damn.
• Barley's just not the right texture. And it's a bit of a pain in the ass to make as a prerequisite to making cookies.
• Expensive. $5 worth of Asagio for 16 cookies?

On the positive side, I do believe that tasty mushroom cookies are possible and I came reasonably close to it on the first try (good taste, wrong texture). Next go I'll make only a half-batch, use less cheese (and use probably Cheddar or Jack instead), a bit less baking powder (more crisp, less chew) and try it with instant rice instead of barley. The rice should be nicely hydroscopic, should brown a bit, should beat the egg proteins up a bit and make for a much better texture.

Further, the extra cheese and mushroom on top was a REALLY good move...