• Preheat the oven to 350°F. Spray a 9x13x2-inch baking dish with cooking spray (I use a glass baking dish; you can also use a metal baking pan).

Make the Pumpkin Layer

• In a large bowl, whisk together the pumpkin, evaporated milk, eggs, ½ cup white granulated sugar, light brown sugar, pumpkin pie spice, 1 teaspoon salt, and vanilla extract until well combined.
• Pour the pumpkin mixture into the prepared baking dish; set aside.

Make & Add the Toppings

• In a medium bowl, whisk together the flour, 1 cup white granulated sugar, baking powder, and ½ teaspoon salt until well combined.
• Evenly sprinkle the flour mixture over the pumpkin mixture, making sure to go all the way to the sides of the baking dish. Do not stir.
I sprinkle on the flour mixture by hand, lightly and a little at a time. You want the mixture to sit on top of the pumpkin mixture and not sink down into it.
• Evenly sprinkle the chopped pecans over the flour mixture.
• Evenly drizzle the butter over the top, covering as much of the flour mixture as possible.
I spoon the butter over the top, a little at a time, for better control as to where it goes. The goal is have as little of the dry flour mixture exposed as possible (a few small spots here and there are okay; the butter will bubble up and cover them during baking).

Bake & Cool

• Place on the middle rack in the oven; bake for 50 to 60 minutes or until the top is golden brown and the cake is set (to test: a toothpick or knife inserted in the middle should come out clean).
Keep an eye on it as you get towards the end of the baking time. If the top is getting too brown before the cake is set, lightly cover the dish with aluminum foil for the remainder of the baking time.
• Place the baking dish on a wire cooling rack and cool completely, about 2 hours. The cake will continue to set up as it cools, which will make it easier to cleanly slice.
• Cut into 12 squares and serve.