In a small bowl, combine flour, baking powder and salt; set aside. In the bowl of an electric mixer, beat butter until smooth, about 1 minute. Add sugar and continue to beat until mixture is light and fluffy, scraping down the sides of bowl as needed, about 2 minutes. Add eggs and vanilla and beat until combined. In two additions, add milk and flour mixture, alternating between the two. Beat until combined. Gently fold in chocolate chips. Transfer batter to prepared skillet and spread into an even layer. Sprinkle with streusel. Bake on the center rack until a toothpick inserted into the center comes out clean and the topping is deep golden, about 50 minutes.