1. Heat oven to 400°F. Spray 15-1/2x10-1/2x1-inch jelly-roll pan with nonstick cooking spray. Line with wax paper; spray again.
2. Sift together flour, cocoa and baking powder. Beat eggs, granulated sugar and vanilla in small bowl until pale in color, about 5 minutes. Fold in cocoa mixture; spread batter into prepared pan.
3. Bake 5 to 7 minutes or until top springs back when touched lightly in center. Invert cake onto clean towel; remove wax paper. Roll up cake with towel from short side. Cool completely on wire rack.
4. Unroll cake; spread with frozen yogurt. Reroll cake without towel; press seam-side down. Cover; freeze until firm. Sprinkle top lightly with powdered sugar, if desired. Cover; freeze leftover cake roll. 12 servings.