Preheat your oven to 350°F (175°C).
In a large mixing bowl, whisk together the granulated sugar, flour, cocoa powder, baking powder, and salt until well combined.
Add the eggs, milk, melted butter, and vanilla extract to the dry ingredients. Mix until the batter is smooth and well incorporated. The batter will be thin.
Stir in the chocolate chips gently.
Pour the batter into a greased 9-inch pie dish, spreading it evenly.
Bake in the preheated oven for 30 minutes, or until the edges are set and the center is slightly fudgy.
Once baked, remove the pie from the oven and let it cool for 10 minutes before serving.
Serve the Hot Fudge Pie warm for a gooey texture, optionally topped with whipped cream or ice cream.