heat oven to 350 degrees! lightly oil a 12 cup bundt pan, then dust with flour. in a large bowl whisk together the flour,pumpkin pie spice,baking powder, salt and baking soda.
in a medium bowl, whisk together the eggs,oil, sugars,pumpkin,milk and vanilla. add the egg-oil mixture to the flour mixture, mixing until fully incorporated. mix in the carrots and walnuts.
transfer the batter to a prepared pan and bake until a tooth pick comes out clean. about 55 to 60 minutes. let cake cool for 15 minutes before transferring to a wire rack to cool completely.
using an electric mixer, beat the cream cheese,butter and vanilla in a large bowl until smooth. add the confectioners sugar and beat until fluffy.
when the cake has cooled completely cut it in half horizontally. spread 3/4 cup of frosting on the bottom half of the cake and sandwich with the top. transfer 1/2 cup frosting to a bowl and tint green.
tint the remaining frosting orange. spread the orange frosting over the cake. refrigerate for 15 minutes. cover the ice cream cone with the green frosting and place in the middle of the cake, it will resemble a stem make it a pumpkin.