Cover the 7x7 square on the left with the 12 L-shaped pieces on the right. You are not allowed to turn over any of the pieces, but you may rotate them in the plane.
Attribution: Nob Yoshigahara
Here goes
. . a a a . . . . a b b . . . . c c b . . . . d c b . . d d d c X e e Y X X X X f e Y Y Y f f f e
Two 2x4 rectangles were left out to make the rest more readable. The two exceptional pieces are X and Y.
Same solution, but in color: