For the Cake:

1. Preheat the oven to 350 degrees and grease a jelly roll pan well (18 by 13 inch baking pan) and set aside.
2. In a medium bowl add the flour, cinnamon, baking powder, soda, salt, all spice, and ginger. Use a whisk to combine well and set aside.
3. In the bowl of your stand mixer add your sugar, oil, and eggs and beat until well combined and thick, about 5 minutes. Add the pumpkin puree and beat until combined, about a minute. Reduce the mixer speed to low and slowly add in the flour mixture. Mix until the mixture just starts to come together (don't over mix).
4. Give the batter a stir with a rubber spatula to make sure it's full combined and then add the batter to the prepared pan. Use the spatula to spread it out evenly in the pan. Bake for 18-22 minutes until the cake springs back lightly when touched and a toothpick inserted into the center comes out clean. Allow the cake to cook before making the icing.

For the Icing:

1. Bring the butter and brown sugar to a boil in a medium saucepan over medium heat, stirring constantly, until the sugar dissolves and the mixture is foamy, 3 to 5 minutes.
2. Whisk in the milk and bring the mixture to a boil and then remove it from the heat. Stir in the powdered sugar and vanilla until the frosting is smooth.
3. Spread the warm frosting evenly over the top of the cool cake and then let it set, about 25 minutes, before serving.