In steamer, steam squash over saucepan of simmering water for 15 to 20 minutes or until tender; let cool. Pulse in food processor until smooth.
In large bowl, whisk together flour, sugar, baking powder, cinnamon, baking soda, and salt. In separate bowl, whisk together buttermilk, egg, 1 tbsp oil and reserved squash; stir into flour mixture just until combined. Fold in pecans.
Brush large, non-stick skillet with some of the remaining oil; heat over medium heat. Pour scant ¼ cup batter into pan for each pancake; cook for about 2 minutes or until golden brown on the bottom and small bubbles appear on top.
Flip over and cook for about 1 minute or until golden brown and set on the bottom. Repeat with remaining batter and oil. Serve with dollop of yogurt and drizzle of maple syrup.