Preheat your oven to 350°F (175°C) and prepare a large sheet pan by spraying it with cooking spray and lining the bottom with parchment paper.
In a large bowl, whisk together the flour, brown sugar, baking powder, baking soda, cinnamon, nutmeg, and cloves, making sure to break up all the chunks of brown sugar.
To a separate bowl, add the pureed pumpkin, buttermilk, eggs, vegetable oil, and vanilla. Whisk these ingredients together until everything is incorporated.
Add the wet ingredients to the dry ingredients and fold them together with a rubber spatula, making sure you don't over-mix (stop folding when no streaks of flour remain).
Pour the batter into the prepared sheet pan and smooth out the top.
Bake for 15-20 minutes or until the top is golden brown and loses its shine.
Let the pancake sit for about 3-4 minutes before slicing into 12-18 large slices. Serve with fresh fruit, maple syrup, whipped cream, a dash of cinnamon, or your favourite pancake toppings.