Working with one breast at a time, cut it into thin strips, about 1/2" each, until you've finished with all four breasts.
Transfer the strips to a medium-large tupperware. Pour the buttermilk evenly out over top, and seal with it's lid. Let the chicken marinate at least two hours, flipping the container once or twice throughout, to ensure an even marinade.
Let the air out of the Doritos bag. Hold the end closed and roll lightly over the chips with a rolling pin once or twice.
Transfer the broken chips to the bowl of a food processor. Lightly pulse until the chips have crumbled and resemble course panko-style crumbs. Turn the chips out onto a large, flat plate.
Add the flour to a separate plate, and use a fork to gently stir in the cayenne pepper-- if using. Beat the eggs in a separate bowl until scrambled. Then line them up in order of use: chicken, flour, eggs, chips.
You can use your fingers, but I recommend a fork to keep the various things from getting clumpy and contaminated. Spear a chicken strip, and let it drip a second or two to remove any excess buttermilk. Dredge them in the flour to coat completely. Shake off any excess flour before dipping them in the egg wash. Again, let any excess drip off, and then transfer them to the plate of Doritos breading.
Dredge until completely coated with Doritos crumbs. Remove the prepared chicken strip to a baking sheet that's been lightly coated with non-stick cooking spray. Repeat until all the strips are done.
Bake the tenders at 400 degrees for 10 minutes. Remove from the oven, use tongs to turn the tenders, and return to the oven. Bake an additional 5-10 minutes, or until the chicken tenders are completely cooked through.
These pair perfectly with a good creamy ranch dressing, for dipping. BUT, if your kids are like mine, they'll want them served with ketchup.