Hershey's Ultimate Brownie Recipe is rich and delicious.
Preheat oven to 350 degrees. Grease a 9x13 pan and set aside.
Stir together cocoa, baking soda in a large bowl and add 1/3 cup butter. Add boiling water and stir until mixture thickens and is well combined.
Stir in sugar, eggs, and remaining 1/3 cup butter. Stir until smooth.
Add flour, vanilla, and salt. Stir until well combined. Stir in chocolate chips.
Pour batter into pan and bake for 28-30 minutes. Let cool completely.
Beat butter in a bowl. Add cocoa and 1 cup powdered sugar. Beat on low to medium speed until combined. Slowly add remaining powdered sugar alternating with milk. Add vanilla. Beat until desired consistency, adding more milk if needed.
Spread frosting on cooled brownies. Sprinkle with more chocolate chips if desired.