Add coconut milk and cornstarch to a small saucepan and heat over low-medium to medium heat, whisking so cornstarch dissolves. Let mixture cook and thicken for about five minutes, stirring occasionally. Add lime juice, vanilla extract, lime zest, sugar, and salt and stir to combine. Let mixture cook for ten minutes or so more, until edges begin to slightly bubble and mixture has thickened.
Remove saucepan from heat and stir in 1 tablespoon butter until dissolved. Let curd cool at room temperature, or place in refrigerator while you prepare the rest of the recipe.
For the bars:
Preheat oven to 350°F. Stir together flour, ground coconut flakes, cornstarch, and salt in a mixing bowl. Cut in butter. You may also use your hands to work butter through evenly by pressing together the dough to form a cohesive ball.
Line an 8" x 8" baking dish with parchment paper, leaving enough overhang on opposite sides so that you will be able to easily pull out bars when ready to slice. Spray parchment paper with cooking spray. Press a little more than half of the batter into the bottom of the pan. Bake for 16-18 minutes, or until dough has slightly browned around the edges and has firmed a bit to the touch.
Pour curd over top of the pre-cooked bottom dough, and place thin layers of the remaining dough on top of curd, in whatever pattern you prefer. Bake for 16-18 additional minutes, or until curd is bubbly and the top dough pieces have cooked. Remove from oven and let cool in pan on a wire rack. After ten or so minutes, place pan in the refrigerator to cool completely before slicing.
Nutritional information is provided as an estimate. As it can vary due to many factors (brands used, quantities, etc.), we cannot guarantee its accuracy.