01 -
Preheat oven to 350°F. In a large bowl, blend melted unsalted butter with granulated sugar until smooth. Add eggs one at a time, whisking well after each, then stir in vanilla extract.
02 -
Sift together flour, cocoa powder, salt, and baking powder. Gradually fold into wet mixture until nearly blended. Stir in cooled brewed coffee and instant coffee granules gently until batter is thick and glossy, avoiding overmixing.
03 -
Pour batter into greased or parchment-lined 9x13" pan and smooth surface. Bake 28–32 minutes until center is just set but fudgy. Cool completely in pan.
04 -
Whisk powdered sugar, milk, and vanilla extract until smooth. Add green gel food coloring until vibrant and desired consistency is achieved, thick yet pourable. Adjust with milk dropwise if necessary.
05 -
Cut cooled brownies into squares. Generously drizzle with green slime glaze immediately before serving for a striking, spooky presentation.