For the Oreo cookie base:

1. Preheat oven to 350 degrees F.
2. Prepare an 8 inch by 8 inch baking pan, see note, and spray the inside with cooking spray.
3. Combine the Oreo cookie crumbs and the melted butter. Press into the bottom of baking pan.
4. Bake in 350 degree F oven for 5 minutes.
5. Remove from oven and let cool slightly while preparing brownie batter.

For the brownie:

1. In a medium mixing bowl, whisk eggs and sugar until blended.
2. Add cooled melted butter and melted chocolate and whisk to combine.
3. Combine dry ingredients in bowl and sift over chocolate mixture. Stir with a wooden spoon or rubber spatula just until combined. Do not over mix.
4. Add semisweet chocolate chunks and stir gently to combine.
5. Pour into baking pan and smooth the top.
6. Bake in 350 degree F oven until set, about 40 minutes. Be careful not to overbake or the brownies will not be fudgy. They should be slightly underdone.
7. Remove from oven and let cool.

For the caramel pecan topping:

1. Combine the butter, corn syrup, and brown sugar in a medium saucepan and heat over medium heat, stirring until melted and combined. Bring to a boil and cook until temperature reaches 240 degrees F.
2. Turn off heat and slowly pour in cream, being careful that it doesn't bubble over.
3. Return to heat and boil until it reaches 248 degrees F. Turn off heat and stir in vanilla, pinches of salt, and pecans.
4. Let caramel cool slightly (it should still be pourable and spreadable). Spread on top of brownies.
5. Let cool to room temperature. Chill in the refrigerator for several hours to firm up.
6. When chilled and firm, slice into squares.
7. Store in the refrigerator.