Grease and flour a 15x10x1-inch baking pan. In a large bowl stir together flour, cocoa powder, baking powder, and salt. Set aside. In a small mixing bowl beat egg yolks and vanilla with an electric mixer on high speed for 5 minutes or until lemon-colored. Gradually add the 3 tablespoons sugar, beating on medium speed about 5 minutes or until sugar is almost dissolved. Wash and dry beaters.

In a large mixing bowl beat egg whites on high speed until soft peaks form. Gradually add the 1/2 cup sugar, beating until stiff peaks form (tips stand straight). Fold yolk mixture into egg white mixture. Sprinkle flour mixture over egg mixture; fold in gently. Spread batter into prepared pan. Bake in a 375 degrees F oven for 12 to 15 minutes or until top springs back when lightly touched. Loosen edges of hot cake from pan; turn out onto a clean dish towel sprinkled with powdered sugar. Starting with a narrow end, roll up cake and towel together. Cool completely.

Unroll cake. Spread softened ice cream onto cake to within 1 inch of edges. Sprinkle with pecans. Reroll cake without towel. Wrap and freeze at least 4 hours. To serve, slice cake. If desired, garnish each serving with berries and mint. Makes 10 slices.