Chocolate Boxes: To preapre milk cartons, cut around sides of milk cartons, 2 inches up from bottoms. Carefully cut down along the four corner seams, just to the bottom, of all 8 cartons. Align edges and securely fasten sides of cartons together with masking tape.

Place 1/2 pound chocolate in medium-size microwave-safe bowl. Microwave on high for 1-1/2 minutes. Stir; microwave 30 seconds. Stir to melt. Let stand 30 seconds; temperature should read about 117 degrees F on instant-read thermometer.

Working fast, pour one-quarter of chocolate into each of 4 boxes. Swirl to coat; use pastry brush to coat inside of boxes. Place, upside down, on baking sheet lined with waxed paper. Refrigerate at least 30 minutes or up to 1 day.

Repeat with remaining chocolate and boxes. Refrigerate.

Unmold: Remove masking tape from a box. Gently peel away carton from chocolate. When all 4 sides have been removed, gently pop bottom of box out of carton. Place box, upside down, on baking sheet. Repeat with remaining boxes.

Mousse: Bring 1/2 cup cream in small saucepan to boiling. Place chopped white chocolate in large bowl. Pour hot cream over chocolate; stir until smooth. Let cool until slightly thickened, about 15 minutes.

Beat remaining cream in bowl until stiff peaks form. Fold whipped cream into cooled chocolate mixture.

Place a finished box, open-side up, on the lined baking sheet. Fill slightly less than half with mousse. Cover mousse with 2 sliced strawberries. Top berries with more mousse until box is filled. Invert dessert plate on top of box; carefully turn both over. Refrigerate filled box until ready to decorate. Repeat with remaining Chocolate Boxes, mousse and strawberries.

Decorate Boxes: For ribbon, fit small basket-weave tip onto tube of desired color of decorating icing. Pipe ribbon onto boxes.

Bows: Fit small plain rose flower tip onto tube of desired color of decorating icing. Pipe bows onto baking sheet lined with waxed paper. Freeze until ready to place on boxes.