Preheat oven to 350° and line an 8X8 baking dish with parchment paper or grease well.
In a food processor (or by hand) pulse graham crackers, toasted coconut, and brown sugar to a fine crumb. Add in melted butter and pulse or combine until mixture resembles wet sand.
Dump crumb mixture into prepared baking dish and press down firmly with hands or the bottom of a glass or measuring cup. Bake for 10 minutes on middle oven rack.
While crust is baking assemble filling ingredients. Using a hand, or stand mixer with the paddle attachment, combine softened cream cheese and sweetened condensed milk for 2 minutes, scraping the bottom and edges of bowl to prevent any lumps.
Add in key lime zest and egg yolks mixing thoroughly. Once fully combined add in key lime juice, vanilla and salt and mix until fully incorporated.
Once the crust is done baking, pour mixture directly onto crust and place back in 350° degree oven for 15 minutes, or until the mixture is set and no longer looks wet in the middle.
Allow bars to cool at room temperature for 30 minutes before transferring to the refrigerator to continue cooling for 2 hours. Once cooled, assemble the whipped cream.
Using the whisk attachment on a stand mixer or a hand mixer, mix heavy whipping cream and vanilla until soft to medium peaks form. Top bars with whipped cream and extra lime zest.
Notes
These bars are easiest to cut straight from the refrigerator when they are nice and cold and are best eaten cold. They can be stored in an airtight container for up to 3 days in the refrigerator.