01 - Preheat the oven to 350°F. Grease a 9x13-inch baking dish and set aside.
02 - In a medium mixing bowl, whisk together flour, baking powder, baking soda, salt, and pumpkin pie spice until well blended.
03 - In a large mixing bowl, beat eggs, granulated sugar, and brown sugar on medium speed until thick and pale, approximately 2 minutes.
04 - Add pumpkin puree, whole milk, vegetable oil, and vanilla extract to the egg mixture. Mix until just combined.
05 - Gradually fold the dry ingredients into the wet ingredients, mixing until just incorporated. Take care not to overmix.
06 - Pour the batter evenly into the prepared baking dish and smooth the top with a spatula. Bake for 30 to 35 minutes, or until a toothpick inserted into the center comes out clean.
07 - Allow the cake to cool in the pan for 15 minutes.
08 - In a bowl, whisk together evaporated milk, sweetened condensed milk, whole milk, and ground cinnamon until fully combined.
09 - Use a skewer or fork to poke holes all over the warm cake. Slowly pour the tres leches mixture over the entire surface, allowing it to absorb.
10 - Cover the dish and refrigerate for at least 4 hours, or overnight, to allow the cake to absorb the milk mixture completely.
11 - Just before serving, beat heavy whipping cream, powdered sugar, and vanilla extract with an electric mixer until stiff peaks form.
12 - Spread whipped cream evenly over the chilled cake and dust with ground cinnamon if desired. Slice and serve cold.