Preheat the oven to 375˚F (190˚C) and position a rack in the upper third. Butter an 8-by-8-inch or similar sized baking dish (or spray it with cooking spray).
Put ½ cup of the oats in a mini food processor, and process to the texture of a coarse flour. Add the brown sugar, cinnamon, nutmeg and salt. Process to combine. Add the pecans and pulse until coarsely chopped. Add the remaining ½ cup of oats and pulse 2-3 times to combine.
Pour the melted butter over the mixture in the processor. Pulse until the butter is distributed and the mixture looks damp, about 2-3 pulses.