Preheat oven to 350F and lightly grease a 9x9 inch baking pan.
In a large bowl, combine the flour, baking powder, apple pie spice, sea salt and stir to combine.
In a small microwave-safe bowl, warm the coconut oil on high for about 30 seconds until melted. Add the flax egg, applesauce, maple syrup, vinegar, vanilla and mix to combine.
Add the wet ingredients to the dry and stir until everything is thoroughly incorporated.
Fold in the cranberries.
Pour the batter into the greased pan and smooth out using a spatula. Then gently press apple slices onto the top if desired.
Bake for about 30 minutes or until lightly brown on the top and a toothpick inserted into the center comes out clean.