For brown butter, carefully slit half of bean and scrape out as much of the insides as you can into a medium skillet. Toss in the butter and scraped out vanilla bean into the pan. Heat over medium heat. Once butter has melted, continue stirring while butter foams up. Once brown flecks appear at the bottom of the pan and the butter has a nutty aroma, remove from heat and set aside, let cool slightly and remove bean shell.
In a food processor, pulse pecans until meal consistency (but not nut butter). Combine with whole wheat pastry flour, baking powder, cinnamon, nutmeg, and salt. Set aside.
In a separate bowl, whisk egg. Whisk in 2 tablespoons slightly cooled brown butter, maple syrup, pumpkin purée and ½ cup of milk.
Combine wet mixture in to dry mixture and stir until batter is combined. Stir in more milk if consistency is too thick, you want the pancake batter to easily pour onto the skillet (but not be too thin).
Heat a skillet over medium heat. When skillet is hot (if you flick water onto the skillet, it should sizzle), take about ¼ cup of batter (I use an ice cream scoop) and pour onto skillet. Let cook for 1-2 minutes (until the pancakes begins to bubble slightly. Flip and let cook for another 1-2 minutes until pancake is cooked through.
Top with remaining brown butter, maple syrup, and pecans.