Start by preheating your oven to 350°F. Grease and flour a bundt pan to make sure the cake doesn’t stick when you take it out later. Set it aside.
In a medium bowl, whisk together the flour, baking powder, baking soda, pumpkin pie spice, cinnamon, and salt. This helps evenly distribute the leaveners and spices throughout the cake.
In a large mixing bowl, whisk together the vegetable oil, granulated sugar, brown sugar, eggs, and vanilla extract until smooth. Then, mix in the pumpkin puree and milk (or buttermilk) until well combined.
Slowly add the dry ingredients into the wet ingredients, stirring until just combined. Be careful not to overmix—you want the batter to remain tender and soft.
Pour the batter into the prepared bundt pan, spreading it out evenly. Bake for 45-55 minutes, or until a toothpick inserted into the center of the cake comes out clean. Once done, let the cake cool in the pan for about 30 minutes before turning it out onto a wire rack to cool completely.
While the cake cools, make the glaze. In a small bowl, whisk together the powdered sugar, cinnamon, vanilla, milk, and maple syrup until smooth. If the glaze is too thick, you can add a little more milk to reach your desired consistency.
Once the cake has cooled completely, drizzle the maple glaze generously over the top. Let the glaze set for a few minutes before slicing and serving.