Make the peanut butter filling. For the traditional filling: In a medium mixing bowl with a hand mixer, or in the bowl of a stand mixer, beat the peanut butter, butter, powdered sugar and salt until they form a very thick paste.

For the alternative filling: Heat the peanut butter, white chocolate, butter and a pinch of salt in the microwave for about 30 to 45 seconds, or until the butter is liquid and the chocolate is starting to melt. Stir until smooth, cover and refrigerate until firm.

Dole out as many 1-tablespoon portions of filling as you can, placing them on a parchment lined plate, trying your best to make them round. Freeze until firm.

Make the cookies. In a large mixing bowl, whisk together the melted warm butter, sugars, baking soda, baking powder and salt. Whisk in the vanilla, egg and cocoa powder until smooth.

Dump in the flour and fold together with the wet ingredients using a rubber spatula, stopping just when the last streaks of white disappear.

Dole out around 16 to 18 balls of dough, about 2 scant tablespoons each (I used my 1.5 ounce scoop but under-filled it.) If the dough is too slack, chill the dough, covered, for 15 minutes in the refrigerator.

Wrap a portion of peanut butter filling in each dough ball, forming the dough around the filling but leaving a half-inch or so of filling visible. Chill the dough balls, covered, for at least an hour.

Preheat oven to 350°F. Line two half-sheet trays with parchment paper. Chill the dough balls again, covered, for 15 minutes in the freezer or 30 minutes in the refrigerator.

Place 6 cookies on a tray and bake on the middle rack for 7 minutes, then rotate the tray and bake for 7 more minutes. Allow to cool on the sheet for 4 or 5 minutes then transfer to a wire rack to cool completely. Repeat with remaining dough balls.