Prep the pan: Line the bottom of a 9-inch springform pan with parchment. Wrap the outside with two layers of foil to keep water out.
Preheat oven to 325°F (163°C).
Make the crust: Mix 2 cups almond flour, 1/4 cup erythritol, 1 teaspoon cinnamon, a pinch of salt, 1 teaspoon vanilla, and 6 tablespoons melted butter until it resembles damp sand. Press firmly into the pan, going slightly up the sides.
Par-bake: Bake crust for 10 minutes until lightly set. Cool while you make the filling.
Beat the cream cheese: With a mixer on medium-low, beat 24 ounces room-temperature cream cheese until smooth, about 1–2 minutes.
Scrape the bowl.
Add sweetener and flavor: Add 3/4 cup erythritol (or 1 cup if you prefer sweeter), 2 teaspoons vanilla, 1–1.5 teaspoons cinnamon, and a pinch of salt. Mix on low until combined.
Add sour cream and cream: Mix in 1/2 cup sour cream and 1/4 cup heavy cream until just smooth. Don’t whip too much air in.
Add eggs: Add 3 large eggs, one at a time, mixing on low after each just until incorporated.
Scrape the bowl and mix 5–10 seconds more.
Pour and prepare the bath: Pour filling over the crust and smooth the top. Place the springform into a large roasting pan. Pour hot water into the roasting pan until it reaches halfway up the springform’s sides.
Bake: Bake at 325°F for 55–70 minutes.
The edges should be set and the center should jiggle like Jell-O, not slosh.
Cool gradually: Turn off the oven, crack the door, and let the cheesecake rest inside for 45 minutes. Then remove from the bath, unwrap the foil, and cool to room temp.
Chill: Cover and refrigerate at least 6 hours, preferably overnight, for the best texture and clean slices.
Make the churro topping: Mix 1/4 cup granular erythritol with 1–1.5 teaspoons cinnamon. Optional: lightly brush the chilled top with melted butter, then sprinkle the “cinnamon sugar” evenly.
You can also press a little around the edge for a churro rim.
Slice and serve: Warm a knife under hot water, wipe dry, and slice. Serve plain or with a drizzle of keto caramel sauce.