Step 1
Preheat the oven to 400 degrees F (200 degrees C). Prick sweet potatoes several times with a fork and place onto a baking sheet.
Step 2
Bake in the preheated oven until sweet potatoes are easily pierced with a knife 50 minutes to 1 hour. Remove from the oven and allow to rest 8 hours to overnight.
Step 3
Preheat the oven to 375 degrees F (190 degrees C).
Step 4
Combine graham crackers walnuts sugar nutmeg and cinnamon in a food processor and blend until crumbly. Incorporate melted butter. Press mixture evenly into a 9-inch springform pan to form a crust.
Step 5
Bake in the preheated oven until golden brown about 10 minutes. Remove from oven and reduce temperature to 300 degrees F (150 degrees C). Let crust cool.
Step 6
Place a cake pan filled with water on the bottom rack of the oven to create moisture and prevent cheesecake from cracking.
Step 7
Combine baked sweet potatoes cream cheese white sugar brown sugar lemon extract vanilla extract nutmeg and cinnamon in a high-powered blender (such as Vitamix®) and process until smooth. Mix in whole eggs and egg yolks on the lowest speed possible; be careful not to overmix filling.
Step 8
Pour filling into crust.
Step 9
Bake in the preheated oven until a tester comes out clean and cheesecake just jiggles slightly in the center about 1 hour and 25 minutes. Leave cheesecake in the oven with the door ajar to allow cheesecake to cool gradually and prevent cracking about 45 minutes.
Step 9
Refrigerate cooled cheesecake for 2 hours before serving.