In a large bowl, mix the first 6 dry ingredients for the cake batter. Whisk in the melted butter, milk, eggs, and vanilla. Pour the batter in the prepared baking dish and bake for 22-25 minutes, until a toothpick inserted into the center of the cake comes out clean. Cool completely before proceeding. *Do not open the oven door before 22 minutes have passed or the cake might collapse.
Meanwhile, toast the coconut by stirring in a skillet over medium heat, until most of the shreds are golden-brown. You could also spread the coconut flat out on a baking sheet and toast it in a 350 degree oven for 6-8 minutes.
Pour the sweetened condensed milk in a medium sauce pot. Unwrap all the caramel squares and add them to the pot. Turn the heat on medium and stir continually until the caramels have melted into the mixture. Stir and simmer a few minutes longer to thicken, then remove from heat.
Pour the caramel over the top of the cake and spread out evenly. Immediately sprinkle the toasted coconut and mini chocolate chips over the caramel. Tap the pan on the counter top to help the coconut settle into the caramel.
NOTES: This cake can sit out on the countertop, covered, for up to three days, or in the refrigerator for up to 10 days. It tasted best at room temperature.