Preheat oven to 350F. Grease and flour three 6″ cake rounds.
In a medium bowl, whisk flour, baking powder, and salt until well combined. This is the dry mixture.
In a stand mixer bowl, cream butter, brown sugar and sugar until pale and fluffy (approx 3mins).
While the machine is on low speed add eggs one at a time fully incorporating after each addition. Add vanilla.
Alternate adding flour mixture and milk, beginning and ending with flour (3 additions of flour and 2 of milk). Mix again until everything is combined.
Toss chocolate chips in 1 Tbsp flour. Fold in chocolate chips and mix until just incorporated. Pour into prepared baking pan.
Bake for 35-40 mins or until a toothpick inserted into the center comes out mostly clean. If you are baking with the 5 baking pan set, bake for 15-20 minutes until the toothpick inserted comes out clean.
Place cakes on wire rack to cool for 10mins then turn out onto wire rack and cool completely.
Milk Chocolate Buttercream
In a stand mixer beat butter until softened.
Add powdered sugar, vanilla and salt and beat until light and fluffy.
Add a tablespoon of milk at a time into the butter.
Add the melted milk chocolate into the buttercream.