Stir together milk and vinegar in a small bowl; set aside to curdle, about 5 minutes.
Combine flour, sugar, baking powder, baking soda, and salt in a large bowl. Whisk in egg and melted butter. Pour in curdled milk and whisk until batter is smooth. Stir in cinnamon and vanilla until well combined.
Heat a large skillet over medium heat and coat with cooking spray. Drop batter, ¼ cup per pancake, onto the hot skillet and cook until bubbles form and the edges are dry, 3 to 4 minutes. Flip and cook until browned on the other side, 2 to 3 minutes. Repeat with remaining batter.
