In a large bowl, whisk together the flour, cocoa powder, sugar, baking powder, ground flaxseed, cinnamon, and salt.
Add the egg, vanilla extract, and milk to a medium bowl. Whisk until smooth and fully combined.
Pour the wet mixture into the dry ingredients. Mix together. Add melted butter and 2 tablespoons of water. Stir until just combined, adding more water as needed for a thick but pourable batter.
Heat a skillet or griddle over low to medium heat. Lightly butter the surface.
Scoop batter using a size 60 scoop, or 1 tablespoon, and pour onto the pan.
Cook until bubbles form on the surface and the bottoms are set, about 2–3 minutes. Flip and cook another 2–3 minutes until cooked through.
Repeat with remaining batter, adjusting heat as needed to prevent burning.
Serve warm with your favorite dips.