Preheat oven to 325ºF. Line a 13-by 9-inch metal baking pan with parchment paper, leaving an overhang on two sides.

In a medium bowl, whisk together the flour, baking powder and salt.

In the bowl of a stand mixer fitted with the paddle attachment, beat the butter and sugar on medium speed until light and fluffy, about 1 minute. Turn the mixer to low, and then carefully add the flour mixture to the bowl, beating just until combined and scraping down the sides as needed. (Do not overmix the shortbread dough or it'll be too crumbly to cut once baked.) Transfer the dough into the prepared baking pan and press it into an even, flat layer.

Bake the shortbread until barely golden, 15 to 18 minutes. Transfer the pan to a wire rack and let it cool completely while you make the topping.

Turn the oven up to 350ºF. Spread the coconut flakes onto a baking sheet lined with parchment paper. Bake the coconut for about 10 minutes until it's toasted, stirring frequently to ensure even browning and so that it does not burn. (See Kelly's Notes.) Remove the toasted coconut from the oven and set it aside.

Melt the caramels, milk and salt in a double-boiler by placing the ingredients in a medium saucepot set over a large saucepot of simmering water. Cook, stirring, until the caramels are fully melted. Remove the saucepot from the heat and combine the caramel mixture with the toasted coconut in a large bowl. Immediately spread the coconut mixture over the cooled shortbread, pressing it to adhere to the shortbread base. Work quickly, as the caramel mixture will begin to firm up and won't adhere if it cools too much. Let the bars sit at room temperature for 30 minutes.

Using the parchment paper overhangs, lift the shortbread out of the pan and onto a cutting board. Slice the shortbread into bars by spacing your cuts to make 3 columns down and 10 rows across to form 30 roughly 2-inch by 1-inch cookie bars.

Melt the dark chocolate in a double-boiler or in the microwave. Dip the bottoms of each of the cookie bars into the chocolate and place them on a wax paper-lined baking sheet. Use a fork to drizzle the tops with chocolate. Let the cookies sit until the chocolate hardens fully.

If you're using dark chocolate chips, 10 ounces is equal to about 1 2/3 cups chocolate chips.

Coconut burns very quickly, so keep an eye on it and stir often!

For an even faster version, skip dipping the bottoms of the cookie bars in chocolate and just drizzle the tops.