Which cocktail is prepared by blending ingredients together and garnished with whipped cream and cherry on top?

The cocktail that is prepared by blending ingredients together and garnished with whipped cream and a cherry on top is indeed the Mudslide. This cocktail typically combines vodka, coffee liqueur (like Kahlúa), and Irish cream, resulting in a rich and creamy texture. Once blended, the drink is often topped with whipped cream and a cherry, enhancing its indulgent and dessert-like qualities.

The other cocktails listed do not fit this description. The Screwdriver is a simple mix of vodka and orange juice, typically served over ice without any creamy garnish. The Pina Colada, while also blended and creamy, is traditionally garnished with pineapple and a cherry, but does not usually feature whipped cream. The Blue Hawaiian is made with rum, blue curaçao, and pineapple juice, blended together but similarly garnished with tropical fruits rather than whipped cream. Therefore, the Mudslide stands out as the cocktail that specifically matches the preparation and garnish described.