4 eggs, separated
1/4 c. sugar
1 tsp. (each) lemon extract, baking powder
1 tbsp. oil
1/2 c. sugar
2/3 c. flour
1/4 tsp. salt

Beat egg-yolks until lemon-colored; gradually add 1/4 cup sugar and beat well; stir in lemon extract and oil; set aside. Beat egg-whites until foamy; gradually add 1/2 cup sugar, beating until stiff; fold into egg mixture. Line a 10x15 inch pan with tin foil; spray foil with Pam. Spread batter evenly on foiled pan. Bake 375 degrees for 10 to 12 minutes. Turn cake out on towel covered with powdered sugar; peel off the foil. Roll up cake and towel together; place on wire rack to cool. Unroll cake; spread with filling and reroll; place on plate, seam-side down; refrigerate for 1 to 2 hours or overnight before serving. Sprinkle powdered sugar on top.

LEMON FILLING:

3/4 c. sugar
3 tbsp. cornstarch
1/4 tsp. salt

Mix, then gradually stir in:

3/4 c. water

Bring to boil for 1 minute stirring constantly. Remove from heat; stir in 1 tablespoon butter and 1 tablespoon grated lemon rind. Add 1/3 cup lemon juice and stir; cool thoroughly.