• Grease a 9 x 13-inch baking dish or pan with butter or shortening. Set aside.

Make the Crust:

• Melt the butter in a small, microwave-safe bowl in 30 second intervals.
• Combine the graham cracker crumbs and melted butter in a small bowl and stir until the crumbs are evenly coated in butter.
• Pour the crumbs into the prepared baking dish, and firmly press them into the bottom using a flat-bottom glass or measuring cup.
• Place the crust in the freezer, while you prepare the layers, for about 15 minutes so it hardens.

Make the Filling:

• Place the cream cheese, sugar and vanilla in a large mixing bowl.
• Use an electric mixer at medium speed to blend everything together until smooth.
• Add in half of the whipped topping and continue blending at low speed until the whipped topping is incorporated.
• In a separate medium or large bowl, pour the sweetened condensed milk, then whisk in the Greek yogurt until combined.
• Whisk in the key lime zest, then gradually add the key lime juice, whisking carefully to avoid splashing the juice out of the bowl.
• Continue whisking until all of the juice has been added.

Assemble the Dessert:

• Spoon the cheesecake layer over the chilled graham cracker crumb base. Spread it out evenly.
• Pour the key lime layer over the cheesecake layer making sure it reaches the edges of the dish.
• Spoon and smooth out the remaining 8 ounces of whipped topping on top of the dessert.

Chill and Serve:

• Cover the dish with plastic wrap, and chill it in the refrigerator for at least 4 hours, but overnight is best.
• Garnish with extra whipped cream and key lime slices and serve chilled.