Toast the sweetened shredded coconut in a large sauté pan over medium-high heat, stirring constantly until golden brown (about 5 minutes). Set aside ½ cup for garnishing.

In a microwave-safe bowl, combine the dulce de leche with 2 tablespoons of milk. Heat in microwave for about 1.5 minutes, stirring halfway through until warm.

Pour the warmed dulce de leche mixture over the remaining toasted coconut in a mixing bowl. Stir well until evenly coated.

In another microwave-safe bowl, combine the mini marshmallows and butter. Microwave for about 2 minutes, stirring until completely melted and smooth.

Once smooth, gently fold in the Rice Krispie cereal until well-coated with the marshmallow mixture.

Grease an 8x12 inch pan. Press half of the rice cereal mixture into the bottom as the base layer. Spread the caramel coconut mixture evenly over it, then top with the remaining cereal mixture.

Melt the semisweet chocolate in a microwave-safe bowl in 30-second intervals, stirring until smooth. Pour over the top layer of treats and sprinkle with reserved toasted coconut.