Pre-heat your oven to the lowest setting and place a parchment-lined baking sheet inside. In a small bowl, mix the brown sugar, pumpkin puree, egg, 1 1/2 cup of buttermilk, and browned butter. In a larger bowl, whisk together the flour, baking powder, baking soda, spices, and salt. Combine the wet ingredients into the dry, mixing until just combined; some small clumps are fine. If you notice your batter is thick, add the remaining 1/2 cup of buttermilk.
In a medium-size nonstick pan, heat a few tablespoons of neutral oil (such as avocado or coconut oil) over medium heat. Once the oil is hot, spoon in about 1/3 cup of batter and let cook on one side until bubbles form in the center. Flip and repeat with the remaining batter, wiping out the pan and occasionally adding fresh oil to avoid getting burned bits on your pancakes. Place the completed pancakes on the baking sheet in the oven to keep them warm.
The use of oil instead of butter is essential here to achieve crisp outsides. Contrary to popular belief, adding oil to butter will not increase its smoke point, so leave it out! Using a large bowl with a hand mixer, whip your heavy cream until it just starts to come together. Add powdered sugar and vanilla and combine. Keep refrigerated until ready for use. Serve with warmed maple syrup, pecans, a pinch of flaky salt, and a healthy spoonful of whipped cream.