1 cup all-purpose flour (spooned & leveled)
1/4 tsp baking soda
1/4 tsp salt
4 oz, semisweet chocolate, chopped
2 Tbls heavy cream
1/2 cup (1 stick) unsalted butter, room temperature
1/3 cup creamy peanut butter
1/3 cup packed light-brown sugar
1. Heat oven to 350, with racks in upper & lower thirds. In a medium bowl, whisk together flour, baking soda, & salt; set aside.
2. Make filling: place chocolate in a medium heatproof bowl set over (not in) a saucepan of simmering water; stir frequently until almost melted. Remove from heat; stir completely melted. Stir in cream; set aside to cool and thicken, about 30 minutes.
3. Meanwhile, using an electric mixer on high, beat butter, peanut butter, and sugar in a large bowl until light and fluffy. Reduce speed to low; add flour mixture, and mix just until blended (do not overmix).
4. Drop dough by heaping teaspoons onto two baking sheets, about 1.5″ apart. With the bottom of a damp glass, lightly flatten each mound of dough into a 2″ round. Bake until golden around edges, 12-14 minutes, rotating sheets halfway through. Transfer cookies immediately to a wire rack to cool completely.
5. With a small offset spatula or table knife, spread bottom of half the cookies with 2 tsp filling each; sandwich with remaining cookies, pressing gently to spread filling to the edge. Let gently to spread filling to the edge. Let set for 15 minutes before serving. (To store, refrigerate cookies, up to 2 days.)