Mix the milk and vinegar and let it sit for 1-2 minutes (this is the "buttermilk").
Whisk together the flour, sugar, baking powder, baking soda, and salt. Whisk the egg, milk, and butter into the dry ingredients until combined.
Heat a nonstick pan over medium heat add 1/2 tbsp of butter.
Pour about 1/3 cup of batter into the hot skillet and spread it (this will be pretty thick). Arrange blueberries on top of the pancake. Cook until you see little bubbles on top and the edges start to get firm. Flip and cook for another 1-2 minutes until the pancakes have risen, are fluffy, and cooked through.