Preheat oven to 350 degrees. In an 8×8 baking dish, prep with nonstick spray or parchment paper and set aside.
In a small bowl, mix the melted Hiland Dairy Butter with the graham cracker crumbs. Mix together until combined. Mixture will look like wet sand.
Pour the crumb mixture into the baking dish and press down into an even layer. Bake the crust in the oven for 6-7 minutes.
Filling: In a stand mixer or with a handheld mixer, mix the egg yolks, sweetened condensed milk, Key Lime juice and lime zest. Mix on medium speed for 2-3 minutes until combined.
Pour the filling over the baked crust and spread out evenly. Place in the fridge overnight to set.
Whipped Topping: In a stand mixer with the whisk attachment or a handheld mixer, add the Hiland Dairy Heavy Cream, sugar and vanilla and mix on medium speed for about 2 minutes or until you have stiff peaks.
Once ready to serve, cut bars and place a large dollop of the whipped topping on each bar. Garnish with a slice of Key Lime and some zest if desired.
Store bars in the fridge when not serving. Enjoy