Preheat the oven to 350°F and line an 8×8 pan with foil and lightly grease. Set aside.
In a medium sized bowl over low heat, melt the butter. Add in the sweetened condensed milk and stir with a whisk. Add in the dark chopped chocolate and continue mixing until everything is smooth and melted. Remove from heat and set aside.
3/4 cups butter, 14 ounces sweetened condensed milk, 3/4 cups dark chocolate
In a large bowl, beat the eggs, egg yolk, vanilla, and both sugars. Whisk vigorously for 2 minutes until light and airy. There should be bubbles forming. You may also use an electric mixer for this part to save elbow grease!
2 eggs, 1 egg yolk, 1 tbsp vanilla, 1/4 cup light brown sugar, 1/4 cup white sugar
Add in the chocolate mixture from earlier and gently fold together. Do not overmix!
Add in the flour, unsweetened cocoa powder, and salt, and continue mixing until no streaks appear.
1/2 cup all-purpose flour, 1/4 cup unsweetened cocoa powder, 1/4 tsp salt
Toss in the broken Oreos and chocolate chips and mix for a few seconds.
1/4 cup semi-sweet chocolate chips, 10 Oreos
Pour into a prepared 8×8 square pan and spread out evenly. Bake for 25-40 minutes or until a toothpick inserted comes out slightly fudgy. (It really depends on your oven with this recipe, so keep an eye on it). If it is wet with batter, continue baking.
Once ready, slightly open the oven door for 10 minutes and allow the hot air to come out. Then completely remove the brownies from the oven and cool on the counter.