I found this recipe at Passionate About Baking.
1/2 cup unsalted butter (softened)
9 oz Hersey's milk chocolate baking chips
1/2 cup sugar
2 large eggs (room temperature)
1 tsp pure vanilla extract
3/4 cup plain flour (sifted)
1 TBsp Hersey's unsweeten cocoa powder
pinch of salt
How to make them:
Preheat oven to 350 degrees.
Line a 9 inch square pan with parchment paper.
Melt butter gently in a microwave safe bowl, add the chocolate chips and let stand for 1 minute.
Stir till well incorporated, leave to cool slightly.
Add the sugar, eggs, and vanilla.
Whisk briskly until mixed well.
Add the flour, cocoa, and salt, stir until smooth.
Spread evenly into prepared pan.
Bake for 20 minutes or until toothpick inserted comes out clean.
Leave in the pan to cool completely.
Remove gently and cut into squares, Enjoy!