Preheat the oven to 350F. Lightly grease and line all (4) sides of an 8x8 baking pan with parchment paper. Set aside.
In a small mixing bowl, add the chopped chocolate, butter and oil. Melt the chocolate mixture either in the microwave on high at 30 seconds intervals or over a double boiler on the stove. Give the melted chocolate mixture a thorough mix and set aside to cool slightly.
In a separate mixing bowl, add the eggs and granulated sugar. Whisk these ingredients together until a thick, pale yellow mixture forms, about 3 to 4 minutes.
Into the bowl with the egg batter, add in the melted chocolate mixture and vanilla extract. Whisk to combine.
Next, add in the flour, cocoa powder, baking powder and salt. Gently, whisk the dry ingredients into the wet mixture until a smooth brownie batter forms. Fold in the chopped chocolate or chips (optional).