1. Whisk cocoa, milk, and half-and-half in a saucepan; place over medium heat. Cook, stirring occasionally, 5–6 minutes or until slightly thickened. Add chocolate, reduce heat to low, and stir until melted. Whisk in powdered sugar; remove from heat.
2. Arrange 2 strawberries and 1 cake cube on each of 8 skewers. Divide sauce into 4 bowls, and serve with 2 skewers.