Preheat your oven to 325°F (163°C). Line the bottom of an 8- or 9-inch springform pan with parchment and lightly mist the sides with nonstick spray.
Make the crust: In a bowl, mix oats (or oat flour), almond flour, sweetener, cinnamon, and salt.
Stir in melted light butter. Add applesauce 1 tablespoon at a time until the mixture holds together when pressed.
Press the crust firmly into the prepared pan. Use the bottom of a measuring cup to flatten it evenly.
Bake for 8–10 minutes, then let it cool while you prepare the filling.
Make the cinnamon swirl: Stir together melted light butter, brown sugar, cinnamon, and vanilla. Set aside. It should be pourable but thick.
Mix the filling: In a large bowl, beat softened light cream cheese with the sweetener until smooth, about 1–2 minutes.
Add Greek yogurt, vanilla, and salt; blend just until combined.
Beat in eggs one at a time on low speed. Do not overmix—this keeps the cheesecake smooth and prevents cracks. Sprinkle in cornstarch and mix until just incorporated.
Assemble: Pour half the cheesecake batter over the crust.
Drizzle half the cinnamon mixture in thin ribbons over the batter. Use a butter knife to lightly swirl—think gentle figure eights. Add the remaining batter and repeat with the rest of the cinnamon swirl.
Prepare a simple water bath: Place the springform pan on a sheet pan.
Pour about 1/2 inch of hot water into the sheet pan around the cheesecake. This helps it bake evenly without soggy crust.
Bake for 40–50 minutes. The edges should be set, and the center should still jiggle slightly when you nudge the pan.
Avoid overbaking.
Cool gradually: Turn off the oven, crack the door, and let the cheesecake sit inside for 30 minutes. Then move it to the counter to cool to room temperature.
Chill for at least 6 hours, preferably overnight. This is when the texture fully sets and flavors deepen.
Glaze: Whisk the powdered sweetener with milk, vanilla, and a pinch of cinnamon until smooth and drizzle-ready.
Release the cheesecake from the pan, then drizzle the glaze in thin lines over the top.
Slice with a warm, clean knife for neat edges. Wipe the blade between cuts.