Preheat your oven to 350°F (about 175°C). Lightly coat an 8×8‑inch baking dish with nonstick spray. Set aside.

In a large bowl, whisk together the flour, pumpkin pie spice, baking powder, salt, and granulated sugar. Set that dry mix aside.

In a separate medium bowl, combine the melted butter, pumpkin puree, milk, and vanilla extract; whisk until smooth.

Combine the wet ingredients with the dry mixture and mix until a thick batter forms.

Spread the batter evenly into the prepared baking dish.

Make the topping:
a. Toast the chopped pecans in a skillet over medium heat until they turn lightly golden and fragrant. Remove from heat.
b. In a medium bowl, mix granulated sugar + light brown sugar; stir in the toasted pecans.

Top the batter with the pecan‑sugar mix. Do not stir.

Pour the hot water carefully over the topping. The hot water will combine with the sugar and run through to sit beneath the cake—this is your sauce.

Place the pan on a baking sheet (to catch potential drips), then bake for 45–55 minutes. The center should be set (not jiggly).

Let the cobbler cool 15‑20 minutes before serving. Scoop out portions so sauce from underneath is drawn up, and serve with vanilla ice cream or whipped cream as desired.