Preheat the oven to 350 degrees F.
In a small bowl, whisk together flour, baking powder, salt and baking soda. Set aside.
In a large bowl, cream together butter and sugars, beating until light and fluffy.
Beat in eggs, one at a time, until smooth. Add vanilla & mix in.
Gradually add flour mixture to wet mixture, scraping down the sides of the bowl after each addition.
Stir in chocolate chips, reserving a handful.
Spread the dough evenly in a 10-inch cast iron skillet. Scatter the reserved chocolate chips on top.
Bake about 25-30 minutes, until the center is cooked through and a toothpick inserted in the center comes out clean.
Remove from the oven and cool slightly.
Serve warm with vanilla ice cream and toppings if desired.