Preheat the oven to 425°F (220°C).
Lightly grease a 13 × 18-inch rimmed sheet pan or line the bottom with parchment paper.
Whisk the flour, baking powder, sugar, and salt together in a large bowl.
In another bowl, whisk together the milk, eggs, melted butter, and vanilla.
Pour the wet ingredients into the dry ingredients and gently stir until just combined. Do not overmix.
Pour the batter into the prepared sheet pan and gently spread it into an even layer.
Scatter blueberries, strawberries, chocolate chips, or other desired toppings over the batter.
Bake for 12–15 minutes until puffed, lightly golden around the edges, and cooked through in the center.
Allow to cool for 2–3 minutes.
Slice into squares or rectangles.
Serve warm with butter, maple syrup, fresh fruit, or your favorite pancake toppings.