• Preheat oven to 350.
• Grease bottom only of 10" x15" jelly roll pan. Line with parchment paper and grease and flour the whole pan.
• In small bowl, combine flour, cocoa, baking powder, and salt. Set aside.
• In separate small bowl, beat egg whites until foamy. Gradually add half of the sugar, beating continuously until stiff peaks form. Set aside.
• In large bowl, beat egg yolks until thick. Add remaining sugar and vanilla; beat until very thick. Stir in water. Add flour mixture gradually, folding into egg yolk mixture after each addition. Gently fold in beaten egg whites.
• Spread batter in prepared pan.
• Bake for 14 to 16 minutes or until cake springs back to the touch.
• Loosen edges and immediately turn cake onto towel dusted with powdered sugar and remove parchment paper. Starting at the narrower end, roll up cake iin towel; cool completely.

Filling

• In medium bowl beat cream cheese, cool whip, powdered sugar and vanilla until smooth and creamy. Set aside.

Frosting

• In medium bowl, cream butter. Add cocoa, powdered sugar, salt, vanilla and milk and mix until smooth and creamy. Set aside.

Assemble

• Unroll cooled cake; remove towel.
• Spread cake with filling.
• Roll up again, rolling loosely to incorporate filling.
• Frost filled roll.
• Cover and refrigerate.