In the bowl of a stand mixer fitted with a dough hook attachment, combine the warm water and granulated sugar. Add the bread flour, cinnamon, active potato flake sourdough discard, oil or butter, and salt. Mix on low speed until combined and no dry spots remain. The dough will be very shaggy and wet.
Transfer the dough to a large bowl that has been lightly oiled with coconut oil or butter. Cover it with plastic wrap and let it rise in a warm place for 8-10 hours, or until it has doubled in size. The dough rise time can vary depending on the temperature of your kitchen.
The next morning, or once the dough has risen, brush a 13x9-inch baking dish with 2 tablespoons of melted butter and set it aside.
Use a bench scraper to scrape around the sides of the bowl, deflating the dough. Transfer the dough to the center of the prepared 13x9-inch pan. Press with your fingers into the dough to stretch it until it about fills the pan.
Cover with plastic wrap and let it rise again for 5-8 hours, or until doubled in size and the dough fills the pan.
Near the end of the rise, preheat your oven to 450°F.
Melt the butter in a small saucepan over low heat. Remove from heat and stir in the brown sugar and cinnamon until well combined. You could easily cut the "goo" ingredients in half if you have less of a sweet tooth or prefer to for health reasons, it will still be delicious!
Drizzle the butter, cinnamon, sugar, and brown sugar mixture evenly over the top of the dough.
Oil your hands with coconut oil and press deep dimples all over the dough. It will look a bit messy, but that’s okay!
Bake the focaccia for 25-30 minutes, or until it is golden brown and crusty.
Let the focaccia cool for 10 minutes in the pan, then transfer it to a cooling rack to cool fully.