Preheat the oven to 275 degrees F and grease a 9x13 baking pan.
Measure the flour into a large bowl using the spoon and level method so it isn't packed down. Add the sugar, salt and baking soda, then give the dry ingredients a quick whisk to break up the flour.
Add the eggs one at a time. Open the can of fruit cocktail and pour just the juice into the bowl, setting the fruit aside.
Stir by hand for 1 to 2 minutes until the batter is smooth and completely free of lumps. No mixer is needed.
Gently fold in the fruit cocktail until it is evenly distributed through the batter.
Pour the batter into the greased 9x13 pan and spread it out evenly.
Mix the brown sugar and chopped pecans together in a small bowl, then sprinkle the mixture evenly over the top of the batter.
Bake at 275 degrees F for 40 to 60 minutes, checking at 35 minutes. Mine took 48 minutes. The cake is done when a toothpick inserted in the center comes out clean and the top is golden brown.
While the cake finishes baking, combine the butter, sugar and evaporated milk in a small saucepan over medium heat. Add the coconut and cook for about 8 minutes, stirring often, until the sauce is hot and bubbly.
Remove the cake from the oven and immediately pour the hot sauce evenly over the top, lightly spreading the coconut so it covers the whole cake.
Let the cake sit for at least 1 hour so the sauce soaks all the way down into it before slicing and serving. It should be barely warm at the bottom of the pan when it is ready.