Melt 4 tablespoons of butter and set aside to cool.
Whisk the flour, brown sugar, pumpkin spice, baking powder, baking soda, and salt together in a large bowl. In a large measuring cup or bowl, whisk the buttermilk and eggs.
Pour the wet ingredients into the flour mixture and fold together until almost combined, but some streaks of flour are still visible.
Drizzle in the cooled, melted butter and mix until just combined. some lumps are normal. Set the batter aside to rest for 10 minutes.
Heat a large nonstick skillet over medium-low heat, or an electric griddle to 300°F. When warm, add a teaspoon or so of butter or oil and spread across the surface of the pan or griddle.
Drop ¼ cup scoops of pancake batter into pan. It will spread out just a bit. After 2-3 minutes, bubbles will start to form on the edges and surface of the pancake.
When the bubbles on the edges look dry and airy, use a thin pancake spatula to gently lift one side and peek underneath. If the pancake is golden brown, flip and cook on the other side for 2 to 2 ½ minutes, or until the bottom of the pancake is golden brown.
Place cooked pancakes in a pancake or tortilla warmer, or on a plate with a large bowl turned upside down over the top, to keep them warm while you make the rest of the pancakes.
Serve with warm maple syrup. Add a bit of whipped cream and a sprinkle of pumpkin spice sugar, if desired.