Preheat the oven to 350 degrees F and lightly grease a 9 x 13 inch pan.
In a large bowl, whisk together the flour, sugar, baking soda, baking powder, cinnamon and salt.
Now pour in the melted coconut oil, applesauce and vanilla and stir until combined. The dough will be very stiff, not like most cake batters. This is because the fresh apples will provide a lot of moisture as the cake bakes.
Fold in the diced apples and nuts. Use your hands if needed to get them incorporated.
Press the cake batter into the pan, evenly. Bake for 45-50 minutes, or until golden brown and a toothpick inserted comes out clean. Let the cake cool while you prepare the caramel drizzle.
Make the caramel drizzle: In a small pot on the stove, add the vegan butter, brown sugar and non-dairy milk. Heat over medium heat until the butter melts. Bring to a boil and stir constantly, being careful not to let the mixture overflow. Continue to boil for 2 minutes, stirring, then remove from heat.
After the cake has cooled for about 20 minutes, drizzle the caramel sauce over it. Let cool for 10 more minutes before serving. Enjoy!