Heat the oven to 350 degrees. Lightly coat a 13x9-inch baking pan with non-stick cooking spray. Combine the graham cracker crumbs and pecans in a food processor. Pulse until the nuts are finely ground. Add the butter and pulse until combined. Press into the pan. Bake for 10 minutes and then cool on wire rack for 5 minutes. Combine 8 ounces cream cheese, 1 cup sour cream and 1/2 cup sugar in a large bowl. Beat at medium-low speed until smooth. Add 2 eggs, one at a time, beating just until combined. Pour over the crust in the pan. In the same bowl, combine 8 ounces cream cheese, pumpkin, pumpkin pie spice, vanilla extract, 1/2 cup sour cream and 1/2 cup sugar. Beat at medium-low speed until smooth. Add 2 eggs, one of at time, beating just until combined. Gently pour over the prior layer, spreading to cover. Bake for 30 to 35 minutes or until the edges are puffed and top is dry to the touch and the center is lightly set. Cool on a wire rack to room temperature. Refrigerate for 4 hours or overnight until thoroughly chilled. Beat whipping cream, ¼ cup sour cream, and 1 tablespoons sugar in a medium bowl at high speed until soft peaks form. Spoon over each serving before serving.