Heat oven to 350°F. Grease bottom only of 13x9-inch pan with shortening. In large bowl, stir brownie ingredients until well blended with spoon. Spread in pan.
Bake 24 to 26 minutes or until toothpick inserted 2 inches from side of pan comes out almost clean. Cool completely, about 30 minutes.
In large bowl, beat filling ingredients until smooth. Spread over cooled brownies. Cover; refrigerate at least 2 hours or until set.
To serve, spoon pie filling over top. Cut into squares.