Pre-heat oven to 375f or 190c.Place milk and vinegar together in a large sized bowl. Stir and leave for a couple minutes while you prepare the dry ingredients (this makes a buttermilk). We will come back to this in the third step.Add the flour, baking powder, baking soda and salt to a medium sized bowl.Melt the coconut oil if it is not already in a liquid state. Add the remaining "wet" ingredients (sugar, maple syrup, applesauce, apple, vanilla, cinammon, coconut oil) into the large sized bowl to the milk and vinegar mixture. Whisk together until everything is well mixed.Mix the dry ingredients together so that the baking powder, soda, salt and flour are evenly distributed. Slowly add to the wet ingredients. Carefully fold the wet over the dry ingredients until they are just mixed together. Make sure not to over-mix to ensure a soft muffin.In the medium sized bowl, where you mixed your dry ingredients, add the crumble ingredients and mash them together using a fork until you get a crumbly, slightly wet texture. Add a titch more flour or oil/applesauce if mixture is too wet/dry (I added applesauce to avoid adding extra oil).Grease your muffin pan using a non-stick cooking spray or coconut oil. Sprinkle cinammon and sugar on the bottom of the pan. Scoop batter into muffin tins (about 2 heaping tbsp in each). Sprinkle streusel on top. Pop in the oven for about 17 - 22 minutes for muffins or about 38 - 45 minutes for a cake in a square pan. Take out of the oven once a toothpick is almost clean and the edges of the muffins are a slight golden brown. Let sit in the pan for about 30 minutes until they have cooled down. Devour :D