Makes 30 to 36 cookies.
Preheat the oven to 200 degrees. Position racks in the upper and lower thirds of the oven
Combine the egg whites and cream of tartar in a clean dry bowl. Beat at medium-high speed with a heavy-duty stand mixer (or high speed with a hand mixer) until the egg whites are creamy white (instead of translucent) and hold a soft shape when the beaters are lifted. Continue to beat on medium to high speed, adding the sugar a little at a time, taking 1 1/2 to 2 minutes in all, until the whites are very stiff. Scatter small spoonfuls of peanut butter over the meringue. With a large rubber spatula, fold about three strokes. Scatter the nuts and chocolate over the batter and continue to fold until they are dispersed and the peanut butter is mostly blended; a few uneven streaks of white meringue are okay.
Drop rounded tablespoons of meringue 1 1/2 inches apart on the lined cookie sheets. Sprinkle each meringue with a pinch of the chopped peanuts. Bake for 1 1/2 hours. rotate the pans from top to bottom and from front to back halfway through the baking time to ensure even baking. Remove a test meringue and let it cool completely before taking a bite (meringue are never crisp when hot.) If the test meringue is completely dry and crisp, turn off the oven and let the remaining meringues cool completely in the oven. If the test meringue is soft or chewy or sticks to your teeth, bake for another 15 to 20 minutes before testing another.
To prevent cookies from becoming moist and sticky, put them in an airtight container as soon as they are cool. Cookies may be stored in an airtight contain for at least 2 weeks.