Preheat the oven to 425F with the top oven rack in the middle position. You don't want the racks too high up close to the heat source. Line a baking sheet (18 x 14) with parchment paper and spray or use a little butter over the parchment, just enough to grease it a little.
Make the pancake batter:
In a large bowl, combine the flour, baking powder, sugar, and salt. Make a well in the middle and add the milk, eggs, melted butter, and vanilla. Whisk to combine until mostly smooth. The batter is thick and airy.
Pour the batter on top of the parchment paper and gently spread it evenly with a spatula. You don't need to go all the way to the edges, just make an even layer.
Distribute the strawberries on top of the batter and gently press them down a little. Sprinkle chocolate chips over the top.
Bake:
Bake in the preheated oven for 12 minutes, until the middle of the pancake is puffy and the top is golden brown. Remove the pan from the oven.
Serve:
Using a knife or frosting spatula, go around the edges of the sheet pan. Slice into squares and serve.
Notes
Use the right baking powder: Since pancake batter naturally has a mild, neutral flavor, it's important to use aluminum-free baking powder. The metallic flavor will ruin the taste, especially in fluffy pancake recipes that call for 2 or more teaspoons. Trust me on this one.