In a medium saucepan, melt the unsalted butter over medium heat. Once melted, stir in the granulated sugar and cocoa powder. Cook the mixture, stirring constantly, for about 2-3 minutes until everything is smooth and well combined.

Slowly pour in the milk and vanilla extract, stirring continuously. Bring the mixture to a gentle simmer, and cook for another 2-3 minutes. This helps the flavors meld together and ensures your brownies are nice and creamy.

Remove the saucepan from heat and stir in the graham cracker crumbs until they’re fully incorporated. The crumbs will absorb the chocolatey mixture, giving your brownies that perfect texture.

Add the semi-sweet chocolate chips to the mixture and stir until they’re fully melted and the batter is smooth. This will give your brownies a rich, fudgy consistency.

Line an 8x8-inch square pan with parchment paper or lightly grease it. Pour the brownie mixture into the pan and press it down evenly using a spatula. Make sure it's compact to ensure a nice, firm texture once chilled.

Place the pan in the refrigerator for about 2 hours, or until the brownies have set and firmed up. If you’re in a hurry, you can pop them in the freezer for about 30 minutes for a quicker set.

Once your no bake brownies have chilled, cut them into squares and serve. Enjoy the rich, fudgy goodness with a glass of cold milk or a scoop of ice cream!