Grease and flour a 10 inch Bundt pan or spray it with baking spray.
In the large bowl of a stand mixer fitted with the wire whisk attachment mix: flour, 2 cups sugar, salt, pumpkin spice and baking powder. Blend in eggs one at a time, butter followed by vanilla extract and canned pumpkin. Beat for 3 minutes at medium speed, stop and scrape the sides of the bowl ensuring the batter gets uniformly mixed. Pour batter into prepared pan.
Bake in preheated oven for 60 - 70 minutes, or until a wooden toothpick inserted into center of the cake comes out clean. If the top starts to look golden brown and the cake is still not done, cover it with aluminum foil to avoid burnt edges and continue baking, checking on the cake every 5-7 minutes. Once baked, place cake on a wire rack and let it cool before removing from pan.
To Make Rum Glaze:
In a medium bowl combine powdered sugar and rum, mix with a whisk or spoon until fully blended and without lumps. Mixture should be a stiff glaze, but still pourable. If the glaze is too thick, thin with a bit of rum or milk. Using a spoon, drizzle the glaze all over the cooled cake. Let the cake sit until the glaze has hardened.