Preheat the oven to 350 degrees F and position a rack in the middle of the oven. Lightly grease a mini muffin tin with nonstick spray.
In a medium sized bowl, combine together the coconut, egg whites, and sugar, stirring until well combined. Scoop a heaping tablespoon of the coconut mixture into each well of the mini muffin tin. Use a spoon to help get the coconut mixture up the sides and around the bottom. Bake the mini macaroon shells in the oven for about 20-25 minutes until they are just turning golden brown around the edges. If you notice that they’re getting too brown before the time is up, simply use place a sheet of aluminum foil to lightly cover the tops of the mini tartlet shells.
Once baked, let the tartlet shells cool completely on a wire rack. When cooled, fill each tartlet shell with about a teaspoon of the lemon curd (or your other favorite flavor), and top with a fresh blackberry. Enjoy!