1 lb (4 sticks) unsalted butter
1 lb semi-sweet chocolate chips or chopped semi-sweet chocolate
6 ounces unsweetened chocolate, chopped
2 Tbs instant espresso powder
7 large eggs [I substitute a cornstarch slurry.]
2 Tbs pure vanilla extract
2¼ cups granulated sugar
1¼ cups all-purpose flour, divided
1 Tbs baking powder
1 tsp salt
4 cups broken Oreos (about 40 cookies- 1 package)
1. Preheat oven to 350°F. Butter and flour 12×18x1-inch pan. Line with foil or parchment that hangs over the sides for ease in getting them out (butter the foil/parchment).
2. In a heatproof, medium-bowl set over a saucepan of simmering water, heat butter, and chocolates until melted and smooth; cool slightly.


3. In a large bowl, whisk together the eggs, espresso powder, vanilla and sugar. Stir the egg mixture into the slightly cooled chocolate mixture. Cool to room temperature.

4. In a medium bowl, sift together 1 cup of flour, baking powder, and salt, then add to batter. In a small bowl, stir Oreos and remaining ¼ cup flour. Stir cookies into chocolate mixture. Then pour into prepared baking pan and smooth top with a rubber spatula.



5. Bake for 25 to 35 minutes, or until toothpick inserted in center comes out clean with a few crumbs attached; do not overbake! Let cool completely, then cover tightly and chill overnight. Chilled brownies are easier to cut. Dump the chilled brownie pan onto a large cutting board, peel off the foil and cut into squares.

Source:
Recipe GirlReview: Um, let's see. Butter + Chocolate + Espresso + Oreos = Gross? NOPE. Wrong answer. Butter + Chocolate + Espresso + Oreos = PURE GOODNESS. I made this for a friend's baby shower, and it was a hit! It yields a ton of brownies, so be prepared to gain a few pounds. Just sayin'.