Add the sugar, flour, cocoa, powdered sugar, chocolate chips and salt to a medium mixing bowl and mix together well.
1-½ Cups Granulated Sugar, ¾ Cup All Purpose Flour, ⅔ Cup Unsweetened Cocoa Powder, ½ Cup Powdered Sugar, ½ Cup Semi-sweet Chocolate Chips, ¾ teaspoon Salt
Add the Eggs, melted butter (cooled), oil and vanilla to a large mixing bowl and mix together well.
2 Each Large Eggs, ½ Cup Unsalted Butter, 2 Tablespoons Vegetable Oil, ½ teaspoon Vanilla Extract
Add the dry ingredients from step 1 to the wet ingredients in step 2 and stir carefully until just combined.
Line a greased 8x8" Baking pan with parchment paper and lightly spray with cooking oil.
Spread the brownie batter into the baking pan evenly. Bake in the preheated oven for 40 minutes.
Remove and allow to cool completely.
In a large mixing bowl add the softened stick of butter and beat until creamy.
½ Cup Unsalted Butter
In batches (so you don't make a mess) add the powdered sugar. Then the vanilla and milk.