Step 1

Heat oven to 350°F. Spray bottom of 13x9-inch pan with cooking spray.

Step 2

Make brownie batter as directed on box. Stir in 1/2 cup chocolate chips. Spread in pan. Bake 22 to 25 minutes or until toothpick inserted 2 inches from side of pan comes out almost clean. Cool completely, about 1 hour.

Step 3

In large bowl, beat Filling ingredients with electric mixer on medium speed until smooth, scraping down sides of bowl frequently. Spread evenly over brownies. Refrigerate about 2 hours or until set.

Step 4

When ready to serve, cut brownies into 6 rows by 4 rows. In chilled medium bowl, beat 1 cup whipping cream with electric mixer on medium-high speed until slightly thickened. Reduce speed; beat in 3 tablespoons powdered sugar and 1/2 teaspoon vanilla. Increase speed; beat mixture until stiff peaks form.

Step 5

Spoon whipped cream into decorating bag fitted with 1/2-inch star piping tip. In center of each brownie, apply steady pressure to bag while squeezing, and pipe in tight circle to make rosette flower about 1 1/2 inches in diameter. Stop squeezing, and quickly lift bag off. Garnish rosettes with chocolate chips. Store loosely covered in refrigerator.