2. In a saucepan, over low heat, melt together butter and chocolate chips; stirring constantly until smooth.
3. Beat together eggs, sugar and vanilla extract. With mixer running, add in melted chocolate mixture.
4. In a small bowl, combine flour, salt and baking powder. Slowly add into chocolate and egg mixture; mixing until just combined. Fold in semi-sweet chocolate chips.
5. Drop by spoonfuls onto baking sheet lined with parchment paper. Bake for 10-12 minutes. Remove from oven and let cool.
6. Spread cookie butter on bottom of cooled cookie and top with a second cookie.
Notes
You can find cookie butter at most grocery stores and Trader Joe's also has its own version.