In medium bowl stir together flour, baking soda, cinnamon, and salt. In large bowl stir together eggs and sugar. Stir in squash, buttermilk, oil, zest, and vanilla. Whisk in flour mixture just until smooth.
Lightly coat waffle iron with nonstick cooking spray. Pour batter, about ½ cup for each 4-inch square waffle, onto iron, spreading quickly. Cook according to manufacturer's instructions.
Place finished waffle on baking sheet in oven to keep warm. Make remaining waffles, coating waffle iron with cooking spray as needed. Serve hot with fresh fruit or hot maple syrup.