Emeril Lagasse says:
The type of coconut that most folks use, (sweetened, flaked coconut), is best toasted in a moderate oven (300°-350°F) by placing a single layer onto a baking sheet and baking until crispy and golden brown around the edges. Be careful - this doesn't take long! It's best to keep a watchful eye on the baking sheet so that you don't overcook the coconut. For the most even browning, remove the baking sheet midway during the cooking process and toss the coconut, then return the baking sheet to the oven until evenly browned and crispy. Hint: the coconut crisps up more as it cools.
~Lisa