½cup (1 stick or 113 g)butter, at room temperature
1cup (5 oz or 101 g)marshmallow cream
2tspsvanilla extract
1¼cups (156 g)powdered sugar
Glaze and Garnish
6oz (170 g)semi-sweet chocolate, chopped
6tbsp (85 g)butter
1tablespoonlight corn syrup
2oz (57 g)white chocolate, finely chopped
1teaspoonvegetable or canola oil
Instructions
Make Brownie Batter
Preheat the oven to 350° F.
Grease a 9 by 9-inch square baking pan and line it with parchment paper, leaving an overhang so you can lift the brownies out. Set aside.
In a stand mixer or with a handheld mixer, add eggs, both sugars, melted butter, oil, and vanilla. Whip on high for 5 minutes or until doubled in volume and thick.
Sift the flour, cocoa powder, and salt over the bowl and gently fold it in. Pour batter into prepared pan and smooth the top. Bake for 40-45 minutes, or until a toothpick inserted into the center comes out with some crumbs attached. Cool completely.
Make Frosting
In a large bowl, beat butter and marshmallow cream until smooth. Add vanilla extract and powdered sugar and continue beating for 2-3 minutes until light and fluffy, scraping bowl as necessary.
Frost cooled brownies, smoothing the top with an offset spatula. Chill until firm.
Glaze and Garnish
Microwave the semi-sweet chocolate, butter, and light corn syrup at 30-second intervals, stirring well until completely melted and smooth. Pour glaze over chilled brownies, smoothing the top with an offset spatula. Some will spill over the sides.
While the chocolate is still wet, microwave white chocolate and vegetable or canola oil at 20-second intervals, stirring well until smooth and melted. Pour it into a pastry bag and snip off a small hole at the end. Pipe lines across the chocolate glaze, spacing them about an inch apart. Drag a toothpick through the lines, creating a sort of "feathering" going one way, then reverse and go back to the side of the brownies you started at.
Chill until completely set. Cut into squares, as big or small as you'd like, while cold. Serve at room temperature. Store in an airtight container for up to 3 days or freeze for up to a month.