Add the melted butter to a large mixing bowl. Slowly drizzle in the buttermilk while whisking. This prevents the butter from clumping.
Whisk in egg and vanilla.
Add flour, sugar, cinnamon baking powder, baking soda, and salt, and gently mix together on top of the wet ingredients before whisking it all together, until just mixed.
Scoop onto a griddle preheated over medium heat, spreading batter out as needed. Cook for 4-5 minutes on each side, or until golden brown and cooked through.
Notes
This is a thick pancake batter, and it works best with a scoop. If you prefer thinner pancakes, add 1/4 cup regular milk to the batter.
Leftover cinnamon pancakes can be stored in the refrigerator for up to four days, or for two months in the freezer.