01 - Preheat oven to 350°F. Line an 8x8-inch baking pan with parchment paper.
02 - In a mixing bowl, whisk together melted butter and sugar until combined. Add eggs and vanilla extract, whisk until smooth.
03 - Sift in flour, cocoa powder, and salt. Fold gently until just combined.
04 - Pour batter into prepared pan and smooth the top. Bake for 25–30 minutes, until a toothpick inserted in the center comes out with a few moist crumbs. Cool completely, then cut into 6 squares.
05 - In a small saucepan over medium heat, combine heavy cream, chopped chocolate, butter, and sugar. Stir continuously until the chocolate and butter melt and the mixture is smooth, about 3 to 4 minutes. Remove from heat, then stir in vanilla extract and a pinch of salt.
06 - Place a brownie square in a dessert bowl. Top with a generous scoop of vanilla ice cream. Drizzle with hot fudge sauce. Garnish with whipped cream, nuts, and a maraschino cherry if desired. Serve immediately.