Make milk mixture: In a 2-cup measuring jug or bowl, stir the milk and vinegar (or lemon juice) together, then set aside for five minutes.
Mix dry ingredients: Meanwhile, whisk the flour, sugar, baking soda, and salt in a medium bowl.
Mix wet ingredients: Whisk the egg, vanilla, and almond extract into the milk.
Make the batter: Make a well in the center of the flour mixture. Pour the milk mixture and melted butter into the well, then use a fork to stir until the mixture is smooth and no longer shows clumps of flour.
Add berries: If using fresh blueberries, fold them in. (For frozen blueberries, keep them to the side, as you will add them later.)
Prepare pan: Heat a large skillet (or use a griddle) over medium heat.
Cook pancakes: Lightly brush the skillet with melted butter. Use a ¼ cup measuring cup to spoon batter onto the skillet. Gently spread the batter into a 4-inch circle.
Flip pancakes: When the edges look dry and bubbles start to appear and pop on the top surfaces of the pancake, turn it over.
