To prepare the crust
1-Preheat the oven to 375F: Preheat the oven to 375F. Prepare your 7″ springform pan with baking spray and line the bottom with parchment paper. If using a traditional 8″ to 10″ pie plate, spray with baking spray.
2-Combine graham cracker crumbs, sugar, melted butter,: Combine graham cracker crumbs, sugar, melted butter, and cinnamon in a bowl. Mix all ingredients together until your mixture resembles wet sand. Use the backside of a small measuring cup and your fingers to form the pie crust in your vessel of choice. Once your crust is formed, bake your crust at 375 degrees Fahrenheit for 7-8 minutes before removing from the oven. Drop your oven temp. to 350F.

Key Lime Pie Filling
3-While the crust is baking, whisk together: While the crust is baking, whisk together sweetened condensed milk, lime juice, lime zest, and sour cream until fully combined in a large bowl. Pour pie filling into your pre-baked graham cracker crust after it has cooled for 30 minutes. Bake at 350 degrees Fahrenheit for 13-15 minutes if you are using a 7″ or 8″ springform pan or 6-8 minutes if you are using a traditional 8″ to 10″ pie plate.
4-Refrigerate pie for at least 4 hours: Refrigerate pie for at least 4 hours or up to 24 hours before serving. Serve with whipped cream.