Step 1

Preheat oven to 350F. Grease a baking dish (I used a 1 1/2 quart dish but a 2 quart dish would have been perfect!) and set aside.

Step 2

Combine all the sauce ingredients into a food processor. Puree until smooth.

Step 3

Layer the bottom of the pan with half the chips. Top with half the chicken, half the sauce, half the cheese, and half the tomatillos. Repeat again, but finish off with pepper and mushrooms if using.

Step 4

Bake, uncovered, for 25 minutes, or until cheese is nicely melted and dish is heated through.