Preheat the oven to 350F.
Line the bottom of a 9×9 square pan with parchment paper, leaving a 2-inch overhang on two sides.
Make the crust: In a food processor, combine the oats, coconut, flour, sugar and salt and pulse a few times until the coconut and oats are broken down into a thick flour. Add the coconut oil and pulse to combine. Add the water, 1 tablespoon at a time, until the mixture starts clumping together.
Press the crust mixture into the pan evenly, and bake for 13-15 minutes or until fragrant and light golden brown. Set aside to cool while you make the filling.
Make the filling: Put egg yolks and lime zest in the bowl of an electric mixer fitted with the whisk attachment. Mix on high speed until thick, about 4-5 minutes. Reduce speed to medium and add the condensed milk in a steady stream, mix for an additional one minute. Add lime juice, and mix until just combined.
Pour the filling over the crust, and bake until the filling is set, about 30-35 minutes. Transfer to a wire rack to cool completely, then cover and refrigerate for at least 2 hours.
When ready to serve, whip cream and powdered sugar together until stiff peaks form.
Lift bars out of pan using parchment overhang and top bars with whipped cream. Garnish with lime zest, slice into 16 small squares and serve. Store leftovers in the refrigerator to enjoy the next day.