PREHEAT oven to 350° F. Grease and flour 9-inch round cake pan.
FOR STREUSEL TOPPING:
COMBINE flour, brown sugar and cinnamon in medium bowl. Cut in butter with pastry blender or two knives until mixture is crumbly; stir in nuts.
COMBINE flour, baking powder, cinnamon, baking soda and salt in small bowl. Beat butter and sugar in large mixer bowl until creamy. Add eggs one at a time, beating well after each addition. Beat in pumpkin and vanilla extract. Gradually beat in flour mixture.
SPOON half of batter into prepared cake pan. Sprinkle 3/4 cup Streusel Topping over batter. Spoon remaining batter evenly over Streusel Topping; sprinkle with remaining Streusel Topping.
BAKE for 45 to 50 minutes or until wooden pick inserted in center comes out clean. Cool in pan on wire rack for 10 minutes; remove to wire rack to cool completely.