Preheat oven to 325°F (160°C).

Coat a 9"x 13" baking pan with cooking spray.

Line the pan with foil, letting ends hang over the short sides.

Coat foil with cooking spray.

In a medium bowl, whisk together flour, cocoa, baking powder, baking soda, and salt.

Set aside the flour mixture.

In a large bowl, using an electric mixer, beat melted butter, granulated sugar, and brown sugar until smooth.

Add eggs, Kahlua (or strong coffee), and vanilla extract.

Beat just until blended.

Gradually add the flour mixture, beating until just blended.

Stir in chopped Oreos, chopped milk chocolate candy bar with hazelnuts, semisweet chocolate chips, white chocolate chips, and chopped toasted pecans.

Spread batter evenly in the prepared pan.

Bake for 55-58 minutes, or until a toothpick inserted into the center comes out with moist crumbs.

Cool in the pan on a wire rack.

Cover and chill for at least 2 hours before removing from pan.

Cut into bars and serve.