Enjoy this cookie recipe courtesy of the Martha Stewart Makes Cookies iPad app.

1. Whisk to combine flour, baking soda, and salt in a bowl. In a separate bowl, beat butter, brown sugar, and peanut butter with an electric mixer on medium-high speed until fluffy, 3 to 4 minutes; beat in egg. Reduce speed to low, and gradually add flour mixture, beating just until combined.

2. Shape dough into two 8-inch-long rectangular logs, pressing edges with a ruler to shape. Wrap each in parchment or waxed paper; chill 1 hour.

3. Preheat oven to 350°. With a sharp knife, slice dough ¼ inch thick; place slices on parchment-lined baking sheets, spacing 1 inch apart. Bake, rotating sheets halfway through, until cookies are puffed in center and golden brown around edges, 12 to 15 minutes. Let cookies cool completely on wire racks.

4. Spread 1 tablespoon filling (see below) on underside of half the cookies; sandwich with remaining cookies. Cookies can be stored in an airtight container at room temperature up to 2 days.

Peanut Butter Cream Filling (Enough for 2½ dozen sandwiches)

6 tablespoons unsalted butter, softened
¾ cup confectioners’ sugar
¾ cup smooth peanut butter, preferably natural
3 tablespoons heavy cream
1. Beat all ingredients with an electric mixer on medium until smooth, 2 to 3 minutes, scraping down side of bowl. Use immediately, or refrigerate in an airtight container up to 3 days. Bring to room temperature; stir with a flexible spatula before using.