- Preheat the oven to 350F degrees. 
- Line a 13x9 inch baking pan with parchment paper so that the paper extends up the sides of the pan. 
- In a medium mixing bowl, whisk together 2 cups of the flour and 1 cup of the brown sugar. In a small microwave safe bowl, melt the butter in the microwave. Stir the melted butter into the flour mixture until well combined. 
- Press the crust mixture into the bottom of the parchment paper lined baking pan. Bake at 350F for 12-15 minutes until lightly browned. Remove from the oven and cool for 10 minutes. 
- Reduce the oven temperature to 325F degrees. 
- In a large bowl whisk together the remaining ½ cup of flour, ¼ cup of the brown sugar, 3 eggs, 1 can of sweetened condensed milk, and the vanilla extract. Melt the remaining ¼ cup of butter in the microwave in a microwave safe bowl, then stir into the filling mixture. 
- Add the semisweet chocolate chips and 3 cups of the shredded coconut; stir well. 
- Pour the filling mixture over the baked crust. Sprinkle the top with the remaining 1 cup of coconut. 
- Bake the coconut bars as 325F for 30 minutes, until golden brown on top. 
- Cool the bars in the pan for 10 minutes, then carefully remove from the pan by lifting the sides of the parchment paper and moving the bars to a cooling rack. Cool completely to room temperature, then cut into bars and serve.