First, prepare your workspace by greasing 24 kutsinta molds with oil spray and setting up your steamer with water. Place a clean kitchen cloth under the steamer lid to catch any water droplets, then bring the water to a simmer.
Start the dulce de leche since it takes the longest. Place an unopened can of condensed milk in a deep pot and cover it completely with water, making sure there's at least 2 inches of water above the can. Bring it to a boil, then reduce to a simmer and cook for 1 hour. Remember to maintain the water level. Once done, remove carefully and let it cool completely before opening.
While the dulce de leche cooks, make your kutsinta batter. In a large mixing bowl, combine 1 cup tapioca starch and 1 cup all-purpose flour. Add ¾ cup dark brown sugar and mix well. Pour in 2 tablespoons blackstrap molasses and 2 teaspoons lye water. Gradually add 2 cups water while whisking to prevent lumps. Keep mixing until your batter is smooth. Don't worry that it looks brown – it will darken when cooked.
Pour the batter into your greased molds, filling each about 80% full. Place them in your prepared steamer and steam at medium heat for 15 minutes. Remove from the steamer and let them cool completely before removing from the molds.
While the kutsinta cools, make the coconut topping. Put 1½ cups desiccated coconut in a non-stick pan over medium-low heat. Toast it while stirring constantly until it turns golden brown, about 5-7 minutes. Take it off the heat right away to prevent burning and let it cool.
Once everything has cooled, carefully remove the kutsinta from their molds. Top each piece with a spoonful of the cooled dulce de leche, then sprinkle with toasted coconut. Serve right away or store in an airtight container if serving later.
Remember: The kutsinta will be very soft when hot but will firm up as it cools, so be patient before unmolding. If you're making this ahead, store the kutsinta, dulce de leche, and toasted coconut separately and assemble just before serving.