Preheat your oven to 350 degrees and line a muffin tin with paper liners, set aside.
In a food processor, pulse crackers until they are crumbs and add the butter and pulse until you get a wet sand like mixture. Take about a tablespoon of mixture and place it in each cup of the muffin tin and press it down with the back of a spoon or small glass to compact it in the bottom.
In a bowl add the cream cheese and sugar and mix until smooth. Add eggs one at a time and mix well. Add the salt and vanilla and mix until well combined. **make sure your cream cheese is softened so you get a smooth texture at the end!**
Divide the mixture evenly among the muffin cups. Set aside.
In a bowl, add your diced apples, sugar and cinnamon and give it a good toss and set aside to make the streusel.
In a bowl, add the oats, flour, brown sugar, baking powder, cinnamon and cold butter. Using a pastry cutter or a fork, cut/mix everything together until you get a crumbly texture. Do not overmix! You want to have some buttery clumps.
Top each cheesecake with the apple mixture and then the streusel on top. Pop them in the oven for about 15 to 18 minutes or until the sides are pretty set, allow to come to room temp then place in the fridge for at least 5 hours or overnight for best results.
Remove cupcake liners from each cheesecake bite and they are ready to serve!