01 - 
                Preheat oven to 175°C. Grease a 23x33 cm baking dish with butter or non-stick spray to prevent sticking.
              
              
              
                02 - 
                In a large bowl, whisk together pumpkin puree, granulated sugar, brown sugar, eggs, vanilla extract, pumpkin pie spice, cinnamon, salt, and evaporated milk until smooth and well combined.
              
              
              
                03 - 
                In a separate bowl, combine flour, oats, brown sugar, cinnamon, and chopped pecans if using. Add melted butter and mix with a fork or fingers until clumps form and dry ingredients are coated.
              
              
              
                04 - 
                Pour the filling into the prepared baking dish and smooth the surface. Evenly distribute the topping over the filling. Bake on the middle oven rack for 45 to 50 minutes until the topping is deep golden and the center is set but slightly jiggly.
              
              
              
                05 - 
                Allow the dish to cool on a wire rack for at least 30 minutes to set the filling, making it easier to slice. Serve warm for best enjoyment.