1Heat oven to 350 degrees and butter a 9-by-13-inch metal baking pan. Line the pan with a piece of parchment paper that hangs over two of the sides.
2Melt the butter in a small skillet over medium heat, stirring occasionally until the milk solids turn golden brown and smell toasty.
3Immediately pour the hot butter into a large heatproof bowl, add the brown sugar and whisk for about 30 seconds. Add the eggs, oil, vanilla, cinnamon, nutmeg and salt, and whisk until smooth.
4Whisk in the baking powder and baking soda, then fold in the flour with a spatula. When streaks of flour remain, add the cranberries and 1 cup of the pecans. Stir until combined.
5Transfer dough to the prepared pan and pat into an even layer. Sprinkle the remaining 1/2 cup pecans, turbinado sugar, and optional flaky salt over the dough. Bake until just set and light brown around the edges.
6Set the pan on a wire rack to cool completely before lifting out with the parchment paper to slice.