Step 1: Prepare the Brownies : Preheat your oven to 350°F (175°C). Grease and line an 8x8-inch baking pan with parchment paper. In a mixing bowl, whisk together melted butter and sugar until well combined. Add eggs and vanilla extract and mix until smooth. Sift in cocoa powder, flour, salt, and baking powder. Stir gently until just combined — do not overmix. Pour the batter into the prepared pan and bake for 20–25 minutes, or until the center is set. Let the brownies cool completely before cutting into small squares.

Step 2: Make the Fudge Sauce : In a small saucepan, combine heavy cream, chocolate chips, butter, and sugar over low heat. Stir constantly until the mixture is smooth and glossy. Remove from heat and stir in vanilla extract. Keep warm.

Step 3: Assemble the Sundae : In serving bowls or dessert glasses, layer pieces of brownie at the bottom. Add one or two scoops of vanilla ice cream, drizzle warm fudge sauce generously, and repeat for more layers if desired. Top with whipped cream, a sprinkle of nuts, chocolate shavings, and a cherry on top.