Heat oven to 350 degrees F. Lightly coat 12-cup bundt pan with nonstick cooking spray.
In a medium-size bowl, stir together flour, baking powder and pumpkin pie spice.
Beat together the butter and sugar in a large bowl until light and fluffy. Beat in the pumpkin, eggs and vanilla.
Into pumpkin mixture, alternately beat in flour mixture and milk. Pour into prepared pan.
Bake at 350 degrees F for 57 minutes or until toothpick inserted in the center of the cake tests clean. Cool the cake in the pan on a wire rack for 10 minutes. Remove cake to wire rack to cool completely.
Beat together the cream cheese, confectioners' sugar, milk, lemon zest, lemon juice and vanilla in a medium bowl until well blended and a good glazing consistency. Pour the glaze over top of the cake, letting it drip down the sides.