Preheat your oven to 350° and set a rack in the middle position. Grease a 9-inch square baking pan with butter.

In a medium-size bowl, combine graham-cracker crumbs, ground pecans, and cinnamon. Remove ½ cup of the mixture and set aside (you'll use it later in the topping). Add melted butter to bowl and stir with a fork to combine. Press evenly into bottom of pan and bake until lightly toasted, 10-12 minutes.

While crust is baking, make the filling: Whisk together pumpkin purée, brown sugar, half-and-half, egg, spice, vanilla, and salt. Pour pumpkin mixture over hot crust and return the pan to the oven for 20 minutes.