Peanut Butter & Dark Chocolate Sandwiches

Preheat oven to 350F degrees. Line four baking sheets with parchment paper.

In bowl of stand mixer fitted with paddle attachment, beat peanut butter, brown sugar and baking soda on medium speed until well blended (about 1 minute). Add eggs and vanilla, mixing on low speed until just blended. Shape level tablespoonfuls of the dough into balls about 1 inch in diameter. Arrange balls 2 inches apart on prepared baking sheets. Do NOT press down.

Bake one sheet at a time until cookies are puffed and crackled, but still moist looking (about 11 minutes). Transfer baking sheet to rack to cool for 10 minutes. Using spatula, move cookies to rack and let cool completely. Repeat with remaining cookie dough.

Melt the chocolate and butter in medium heatproof bowl set in skillet with 1 inch of water barely simmering. Stir with spatula until smooth and remove from heat. Set aside until cool and slightly thickened, about 20 minutes.

Turn half the cooled cookies over so they are flat side up. Spoon 2 teaspoons of chocolate filling onto center of each cookie. Top with remaining cookies, flat side down. Press gently on each cookie to spread the filling almost to the edge. Set on rack until filling is firm, about 30 minutes.