In another bowl mix together the milk, oil, egg, vinegar and vanilla.
Add dry ingredients into wet ingredients.
Mix until combined
Pour into prepared pan
Sprinkle top of batter with chocolate chips.
Bake for 30-35 minutes or until a toothpick comes out clean.
Notes
Tips for Making the BEST Chocolate Snack Cake
Pan Size. You can use an 8 inch or a 9 inch square baking dish, the cake will not be quite as tall if using a 9 inch pan and may cook slightly faster. You can also use a 8 inch or 9 8 inch round cake pan.
The cake is done when a toothpick comes out clean.
Allow the cake to cool completely before adding powdered sugar or it will melt into the cake.