Put oats in a food processor and process until finely ground.
In a large bowl, whisk together ground oats, all-purpose flour, whole wheat flour, baking powder, baking soda, sugar, cinnamon, and salt.
Then, in a medium bowl, combine buttermilk, squash puree, and the egg. Whisk until well-combined.
Fold the wet mixture into the dry mixture and stir until just combined, taking care not to over-mix.
Now, on a lightly buttered skillet or griddle, pour about 1/4 C of pancake batter.
Cook for 2-3 minutes, before flipping to cook another 2 minutes. As pancakes are done, keep them warm in a lightly heated oven.