Oreo cookie brownies

My mum brought me an Oreo brownie back from America recently, it was delicious .... probably because of all the hydrogenated fat and e numbers! Anyway once i'd eaten it I wanted more, so I decided to make my own.  The recipe I used was peppermint cookies n' cream brownies from Baking Bites blog.  I used plain Oreo's as opposed to the peppermint ones used in the original recipe.

Makes 36 brownies (or 48 bite-sized brownies)

1 cup butter
6 oz. unsweetened chocolate, chopped
3 cups sugar
1/2 tsp salt
2 tsp vanilla extract
4 large eggs, room temperature
1 2/3 cups all purpose flour
1/3 cup unsweetened cocoa powder
3 cups roughly chopped peppermint oreo-type cookies (approx 18)

Preheat oven to 350F. Line a 9×13-inch baking pan with aluminum foil, and grease lightly.
In a medium-large saucepan over low heat, melt together butter and chocolate, stirring occasionally. Whisk in sugar, salt and vanilla, then turn off heat. Whisk in eggs one at a time, waiting until each is fully incorporated before adding the next. Stir in flour and cocoa powder until mixture is uniform. Stir in peppermint oreo cookies and pour batter into prepared pan. Crush 3-4 additional cookies finely and sprinkle on top of batter, if desired.
Bake for about 35 minutes, until a toothpick inserted into the center comes out with moist crumbs, but not coated with batter.
Cool brownies in pan for about 20 minutes, then lift brownies in the foil out of the pan and place on a wire rack to cool completely before slicing.