Cut the round watermelon slice into 8 wedges and keep them together. Place on a serving dish.
Combine chocolate chips and half-and-half in a medium microwave-safe bowl. Heat in a microwave oven for 25 seconds, then remove and stir until chocolate chips are fully melted into the cream. Continue heating in the microwave in 5- to 10-second intervals if necessary.
Spoon melted chocolate evenly over the watermelon, stopping before the rind. Top with a generous portion of sprinkles.
