Preheat the oven to 350-degrees and grease a whoopie pie pan.
Sift together the flour, sugar, baking soda, and salt into a medium bowl and set aside.
In a large mixing bowl, whisk together the milk, eggs, softened butter, and vanilla. Slowly add the dry ingredients and mix until smooth.
Spoon the batter into the prepared pans. Do not fill the cups more than 2/3’s full. Bake for 12-15 minutes.
Remove from the oven and let set for 10 minutes before turning out onto a rack to cool completely.
Frosting directions
Whisk together the sugar, vanilla and butter, adding the milk as needed. Beat for about 3 minutes until fluffy and thick.
Spoon the frosting into a piping bag and decorate cooled cakes as desired.
To Assemble
Once the cakes are cooled, spread the frosting on the bottom of one side and gently press the top on. Lightly press the mini chocolate chips into the frosting. Refrigerate in an airtight container until ready to serve.