Combine 1 cup of milk and 1 tablespoon of vinegar in a small bowl and let it sit for 5 minutes.

In a large bowl, whisk together 1 cup of all-purpose flour, 2 tablespoons of sugar, 1 teaspoon of baking powder, 1/2 teaspoon of baking soda, and a pinch of salt.

In a separate bowl, whisk together the soured milk, 1 large egg, and 2 tablespoons of melted butter. Fold this into the dry ingredients until just combined.

In another bowl, combine 2 tablespoons of melted butter, 1/4 cup of brown sugar, 1 tablespoon of cinnamon, and 1 tablespoon of flour to create the cinnamon swirl mixture.

Preheat your griddle or skillet over medium heat and lightly grease with butter or oil.

Pour small rounds of batter onto the griddle and drizzle with the cinnamon swirl mixture. Cook until bubbles form, about 2-3 minutes, and then flip for an additional 30 seconds until golden brown.

Transfer the pancakes to a warm plate and serve with powdered sugar or whipped cream if desired.