Creamy Delight Chocolate Spiked Cake

Name: Creamy Delight Chocolate Spiked Cake
Cuisine: American
Ingredients: 1 box Betty Crocker super moist chocolate cake mix; 1 1/4 cups rumchata; 1/2 cup non salted butter; 3 eggs; 1/2 cup milk chocolate chunks; 1 stick non salted butter room temperature; 3 cups powdered sugar; 1/4 cup rumchata; 1 tbsp instant coffee; 1 tbsp dark chocolate syrup