In a large bowl, combine cake mix and gelatin. Add pureed strawberries, eggs, oil, and water, beat at medium speed with an electric mixer until smooth.
Pour into prepared pans, and bake for 20 minutes, or until a wooden pick inserted in center comes out clean. Let cool in pans for 10 minutes. Remove from pans, and cool completely on wired racks.
FOR FROSTING: In a large bowl, beat butter and cream cheese at medium speed with an electric mixer until creamy. Beat in 1/4 cup strawberry puree, reserving remaining for another use. Beat in extract. Gradually add confectioners' sugar, beating until smooth. Note: For pinker frosting add 2 to 3 drops of red food coloring.