In a measuring cup or small bowl, add the vinegar to the milk and set aside to slightly curdle to make acidified buttermilk.
1 cup milk, 1 tablespoon white distilled vinegar
In a large mixing bowl, whisk together the flour, baking powder, brown sugar, and salt.
1 cup all-purpose flour, 2 teaspoons baking powder, 2 tablespoons light brown sugar, ½ teaspoon salt
Add the egg, vanilla extract, and your buttermilk mixture, and whisk until smooth, careful not to overbeat.
1 large egg, 1 teaspoon vanilla extract
Fold in the Fruity Pebbles and transfer batter to a measuring cup or other container with spout for easy pouring (see notes).
½ cup Fruity Pebbles
Add butter to your griddle or pan and allow it to heat up on medium-high until the butter is melted.
3 tablespoon unsalted butter
For the thickest, most perfectly round pancakes, use pancake molds. Pour batter into your molds or freeform circles onto the pan and cook over medium heat. When it's ready to flip, the batter on the uncooked side will start to form little air bubbles. Use a spatula to flip the pancakes, and allow them to cook on the other side for 2-3 minutes.
Repeat steps 6 and 7 until the pancake batter is used up, adding butter before each batch to keep your griddle greased. Serve warm with Cereal Milk Whipped Cream (optional) and maple syrup.