Preheat oven to 350 degrees. Combine first 4 ingredients in a large bowl and mix well with a fork. Set 1 cup aside for streusel topping. Press remaining crumbs into a greased 13×9- inch pan.

Bake for 13 to 15 minutes, until puffy and set. Place pan on a wire rack and cool for 20 minutes.

Place cream cheese in a mixing bowl and beat with an electric mixer for 30 seconds. Add brown sugar, pumpkin, egg, and vanilla extract and beat to blend. Pour filling over cooled baked crust.

Add white chocolate, 1 tablespoon melted butter, and oats to reserved 1 cup streusel and mix. Sprinkle over filling.

Bake for 30 minutes or until center is set. Cool completely before serving. Sprinkle with powdered sugar.

Store in refrigerator.