Preheat oven to 325 degrees. Line a 8×8 inch pan with parchment or foil, set aside.
In a microwave safe bowl, add the butter and sugar. Heat in the microwave on high for about 1 minute and 15 seconds. Remove, stir, and let cool for 5 minutes, then stir in the vanilla extract and cocoa powder.
Add eggs to the warm butter and sugar mixture and mix until incorporated.
In a medium size mixing bowl, whisk together flour, baking soda, cornstarch, and salt. Mix until no flour pockets remain. Remove bowl from stand and fold in the chocolate chips and strawberry slices.
Spread the brownie batter evenly into the prepared pan. Place in the oven and bake for 20-30 minutes or until the brownies are set. Remove from oven and allow to cool for 30-45 minutes before cutting and serving.