Oreo Layer
18 ounces Oreo cookies
1/2 cup pecans
1 cup butter

Chocolate Layer
6 ounces bittersweet chocolate
3/4 cup heavy cream
1 1/2 tablespoons confectioners' sugar
5 tablespoons Kahlua

White Chocolate Layer
6 ounces white chocolate
6 tablespoons heavy cream
1 1/2 tablespoons confectioners' sugar

Chocolate Ganache
6 ounces bittersweet chocolate
3/4 cup heavy cream
3/4 cup butter

Oreo layer: Crush Oreos and pecans in blender until smooth. Add melted butter. Press into the bottom of a 12 x 8-inch pan.

Chocolate layer: In a double boiler, melt chocolate with cream, sugar, and Kahlua. Spread the mixture on the Oreo layer and let cool.

White chocolate layer: In double boiler, melt white chocolate in cream and sugar. Spread evenly over chocolate layer. Refrigerate 15 minutes.

Chocolate ganache: In double boiler, melt chocolate in cream and butter. Spread over white chocolate layer and refrigerate at least 15 minutes.

Cut into 1-inch squares.