To prepare the jicama for this recipe, peel it and dice it into small cubes. Place the jicama in a saucepan and add enough water to cover it. Bring the water to a boil and simmer the jicama over medium heat for about 50 minutes.Alternatively, use an Instant Pot to pressure cook diced jicama with one cup of water for 15 minutes. Allow the pressure to release naturally for approximately 40 minutes. Once the jicama is cooked, turn off the heat and let it sit in the hot water for another 10 minutes. This will allow the jicama to soak up more water and become even softer. EXPERT TIP: Dice the Jicama into 3/4-inch cubes or smaller to soften faster. Place the nuts inside a food processor and pulse a few times to chop them into small pieces roughly. Next, add butter and pulse the mixture until it becomes lumpy.
Add the almond flour, sweetener, cinnamon, and a pinch of salt in the food processor and pulse the mixture until it is grainy, with a few butter lumps dispersed throughout. Keep this mixture aside, or store it in the fridge until ready to use.
Peel and dice the Granny Smith apples slightly larger than the jicama cubes as they will shrink during baking.
Remove about two tablespoons of water from the pot and set it aside in a small bowl. Leave the remaining water in the pot with the jicama, as this will help further soften the jicama during baking and thicken the filling.
Mix the arrowroot with the jicama water until dissolved, then add it to the jicama cubes. Stir in cinnamon, sweetener, butter and lemon juice.
Mix the jicama and apples until evenly distributed. The jicama may appear slightly softer than the apples, but that’s okay as the apples will cook during baking.
Sprinkle the jicama and apples with the topping mixture until most of it is covered. It’s okay if a few apple or jicama pieces peek through.
Preheat the oven to 325°F, place the baking dish in the middle rack, then bake for 20 minutes.
After 20 minutes, cover the apple crisp with foil and bake for 40 minutes or until the topping is golden and the filling is bubbling along the edges. Allow the crisp to cool for 10 minutes before serving.EXPERT TIP: Allow the apple crisp to cool for 10 minutes before serving to give the nutty layer a chance to become crisp.