Grease and flour an 8-inch square baking pan.
Measure all ingredients except chocolate morsels into a large bowl.
Beat at low speed with electric mixer until just mixed; increase speed of mixer to medium and beat 2 minutes, scraping bowl occasionally.
Spread mixture evenly into a greased and floured 8-inch square pan.
Bake at 350° for 25 minutes or until toothpick inserted in center comes out clean.
Evenly sprinkle chocolate morsels over cake; bake 2 to 3 additional minutes until chocolate morsels are melted.
Spread chocolate evenly to frost cake.
Cool 10 minutes, and cut into bars.