Preheat oven to 350 degrees F. Generously grease a pie plate or 9 inch baking pan. Set aside.
To make the topping: Combine the oats, brown sugar, cinnamon and HC Trail Mix in a large bowl until well-combined. Add in the pieces of butter and use your hands to squeeze and combine until the mixture becomes crumbly and resembles wet sand. (Alternatively, you can cut in the butter with a pastry cutter, or place all of the topping ingredients in a food processor and pulse until just blended.) Set aside.
To make the filling: Place apples, cinnamon, nutmeg and vanilla in a large bowl and toss to combine. Allow to sit for 5-10 minutes.
Take 1/3 cup of the topping mixture and toss with the apple mixture. Place the apple mixture in prepared pan and sprinkle evenly with topping.
Bake the crisp on a baking sheet (just in case the filling bubbles over!) for 45-55 minutes, or until topping is golden brown and filling is bubbling. Remove from oven and cool 10 minutes on wire rack. Serve warm with your favourite ice cream.