1/2 c. unsalted butter
one 12-oz bag semi-sweet chocolate chips
1 1/4 c. light brown sugar, packed
3 large eggs
2 tsp. vanilla extract
1/4 c. unsweetened natural cocoa powder
1 1/2 c. all-purpose flour
1 1/2 tsp. baking powder
1/4 tsp. salt
about 8 oz. dark chocolate, diced into 1/2-inch pieces (Baker's baking chocolate preferred)
about 12 large marshmallows, cut in half
1. In a medium bowl, add butter, chocolate chips, and heat to melt for ~1 minute. Stop to check and stir.
2. Allow melted chocolate mixture to stand for 5 minutes to cool slightly.
3. In a separate large bowl, add the brown sugar, eggs, and vanilla. Beat with a handheld electric mixer on medium speed just until blended, ~1 minute.
4. Add the cooled chocolate mixture and beat on medium speed just until combined, ~1 minute.
5. Add cocoa powder, flour, baking powder, and salt. Beat on low speed just until combined, ~1 minute.
6. Cover bowl with plastic wrap and refrigerate for 2 hours, or until dough has firmed up significantly. If you accidentally over-chill it and it becomes too firm, allow bowl to rest on counter until you can scoop it.
7. Preheat oven to 325F. Grease baking sheet.
8. Using a 2-tablespoon cookie scoop form dough mounds and place them on the baking sheet, spaced at least 2 inches apart (I bake 8 cookies per sheet).
9. Flatten slightly and bake for 10 minutes, or until edges and tops have just set, even if slightly under cooked and glossy in the center.
10. Remove baking sheet from oven, add 1 piece of dark chocolate to the center of each cookie, pushing down very slightly just so it breaks the surface and sinks down.
11. Place one marshmallow half on the top of each piece of chocolate on all the cookies, pushing down very slightly so the marshmallow adheres.
12. Return baking sheet to oven and bake for about 5 minutes, or just until marshmallows have puffed.
13. Cookies firm up as they cool. Allow cookies to cool on baking sheet for about 10 minutes before serving.