Preheat your oven to 350°F (175°C) and grease a 9x13-inch baking pan with cooking spray or butter. In a microwave-safe bowl, combine butter, cocoa powder, and sugar. Microwave in 1-minute increments, stirring in between, until melted and smooth. Once melted, mix in salt, vanilla extract, and room temperature eggs until fully incorporated. Gently fold in the flour, spread the batter evenly into the pan, and bake for 30-35 minutes, until a toothpick inserted in the center comes out clean. Let the brownies cool completely in the pan.

While the brownies cool, prepare the mint frosting. In a mixing bowl, beat softened butter until creamy. Gradually add powdered sugar and mint extract, mixing until a dense and smooth consistency is achieved. If desired, add a few drops of green food coloring for a festive touch. Once the brownies are cool, evenly spread the mint frosting over the top layer, creating a nice, smooth finish.

Next, make the chocolate layer by melting the semi-sweet chocolate chips and butter together. You can do this over a double boiler or in the microwave, stirring every 30 seconds to ensure it doesn't overheat. If the melted chocolate is too thick, stir in a little canola oil to reach a smooth, spreadable consistency. Once ready, drizzle and spread the chocolate over the frosted brownies, covering them completely for a decadent finish.

Allow the layered Perfect Mint Brownies to cool completely at room temperature, or pop them in the refrigerator for about 30 minutes for quicker setting. When ready to serve, use a sharp knife to cut them into squares, ensuring clean edges. Enjoy your homemade minty treat fresh, or store them covered in the fridge to maintain their rich flavor and texture.