Split the vanilla bean in half lengthwise with a sharp paring knife and scrape the seeds into a medium saucepan with the cream, milk, sugar, cinnamon and salt over medium heat; whisk to dissolve the sugar (about 4 to 5 minutes).
Remove from the heat and set aside to steep for 30 minutes to infuse the vanilla and cinnamon.
Bring the milk mixture back up to temperature.
In a separate bowl, whisk the egg yolks.
Gradually pour about 1 cup of the hot milk mixture into the egg yolk bowl, while continually whisking to temper the eggs.
Add the tempered egg yolk mixture back to the pan while whisking until it just comes to a simmer.
Remove the pan from the heat, then add the vanilla extract.
Pour the ice cream base through a fine mesh strainer and chill completely either over an ice bath or in the refrigerator.
Spin the ice cream base in a maker according to the manufacturer's instructions.
While the ice cream spins, place 2 ½ cups apple crisp on a cutting board and chop it into small pieces. Make sure there are no large pieces of apple left or they will become icy when frozen.
When the ice cream is finished spinning, Continue this process until all of the ice cream is in the container, then freeze for at least 5 hours, or overnight before serving.
Let the ice cream sit out for 5 to 10 minutes before serving to allow the apple pieces to warm up for the best texture.