Heat oven to 350°F. Unroll 1 can of dough and separate into 2 long rectangles. Place in ungreased 13x9-inch pan; press in bottom and 1/2 inch up sides to form crust. (If using crescent rolls, firmly press perforations to seal.) Bake 5 minutes. Meanwhile, in large bowl, mix walnuts, 1/2 cup of the sugar and the cinnamon.
Spoon walnut mixture evenly over crust. Separate remaining can of dough into 2 long rectangles. Place over walnut mixture; press out to edges of pan. With tip of sharp knife, score dough with 6 lengthwise and 6 diagonal markings to form 36 diamond-shaped pieces, using dough edges and perforations as a guide.
In 1-quart saucepan, mix remaining 1/4 cup sugar, the honey, butter and lemon juice. Heat to boiling. Remove from heat; spoon half of sugar mixture evenly over dough.
Bake 25 to 30 minutes longer or until golden brown. Spoon remaining sugar mixture evenly over hot baklava. Cool completely, about 1 hour. Refrigerate until thoroughly chilled, about 30 minutes. For diamond shapes, cut 6 straight parallel lines down length of pan; cut 6 diagonal lines across straight lines.