Triple-chocolate crunchy cookies

These were an attempt to replicate a store-bought cookie from my childhood for a local cookie contest.  Although they flopped at the contest, my family loves them.  First I make two very crunchy, chocolate cookies with chocolate chips.  Then I sandwich them around a chocolate ganache filling.  For the grownups, I spice the ganache with cinnamon and cayenne.  I also put a little gelatin in the ganache to firm it up, because there's nothing worse than cookie filling that squoozes out the sides when you bite it.

To get the cookies really crispy-crunchy, I used a lot of tricks from this page:  I used white sugar instead of brown, used high-protein flour, melted the butter, and swapped the whole eggs for whites only.  I also added some extra baking soda (as is sometimes done with crackers).  But I ultimately had to resort to double-baking the cookies, biscotti-style, to get them to stay crisp once filled.

In a medium bowl, sift together:

1. 5.25 oz (1 c + 2 T) King Arthur all-purpose flour
2. 1 oz (1/3 c) cocoa powder
3. 3/4 t baking soda
4. 1/4 t salt

In a standing mixer, combine with the paddle:

1. 5.25 oz (3/4 c) granulated sugar
2. 1 stick (8 T) butter, melted
3. 1 egg white
4. 1 t vanilla extract

Mix in the dry ingredients, just until thoroughly combined, followed by

1. 5.25 oz (1 c) chocolate chips

Chill the dough while the oven preheats to 375 F, about 20-30 minutes.  Line three cookie sheets with parchment.  Portion the dough by generous rounded half tablespoons, to give 36 cookies (12 per sheet).  Smash the balls into disks, so the final cookie sandwiches won't be too thick.  Bake each sheet for 14 minutes, one at a time, and let cookies cool on the sheet.  Turn the oven down to 300 F.  (I leave the oven door cracked for ~10 minutes to speed this up.)  Bake the cookies for another 15 minutes to dry them out and make them really crunchy.  You can also consolidate the cookies down to two sheets at this point, and even bake one on the lower rack and one on the other if you're in a hurry.  When they're done, let them cool completely on the cookie sheets.

In the meantime, in a 2-cup Pyrex measuring cup, combine in this order:

1. 1/4 t powdered gelatin (such as Knox)
2. 1/4 t ground cinnamon
3. 1/8 t ground cayenne pepper
4. 1.5 oz heavy cream
5. 6 oz chocolate chips
6. pinch of salt

Microwave on high ~45 seconds, then whisk until smooth.  Let cool on counter until cookies are ready.  Ganache may look slightly oily / broken;  it will be fine, just stir it back together before spreading.  Spread filling on the bottom of one cookie and top with another, to make 18 sandwiches.  Keeps up to a week in a tightly sealed plastic container.