Preheat your oven to 425°F (220°C). Grease a sheet pan with cooking spray or butter.
In a large bowl, whisk together the pancake mix, milk, eggs, melted butter or oil, and vanilla extract (if using). Mix until the batter is smooth.
Pour the pancake batter onto the greased sheet pan, spreading it out evenly with a spatula.
Sprinkle your favorite toppings evenly over the pancake batter. This can include berries, chocolate chips, or any other desired additions.
Bake in the preheated oven for about 12-15 minutes or until the edges are golden brown, and the center is set.
Remove pan from oven and allow the sheet pan pancake to cool for a few minutes in the pan. Then, use a knife or pizza cutter to slice it into squares or rectangles.
Serve the sheet pan pancakes warm with your favorite toppings, such as maple syrup, greek yogurt, or additional fresh fruit.