Prep the pan: Preheat the oven to 325°F (163°C). Line the bottom of an 8- or 9-inch springform pan with parchment. Lightly spray the sides with nonstick spray.
Make the crust: In a bowl, mix the crumbs, cocoa, sweetener, melted butter, applesauce, and salt until the texture resembles damp sand.
Press firmly into the bottom of the pan using the bottom of a measuring cup to compact. Bake for 8 minutes, then set aside to cool.
Melt the chocolate: Gently melt the dark chocolate in the microwave in 20–30 second bursts, stirring between each, or in a double boiler. Let it cool to lukewarm so it doesn’t scramble the eggs later.
Blend the base: In a large bowl, beat the softened cream cheese until smooth and fluffy, about 1–2 minutes.
Add the Greek yogurt and sweetener. Beat again until creamy and no lumps remain.
Add flavor and eggs: Beat in the vanilla, almond extract (if using), cocoa powder, and salt. Mix in the eggs one at a time on low speed just until incorporated.
Do not overbeat; too much air can cause cracks.
Add chocolate and milk: Pour in the melted chocolate and the milk. Mix on low just until the batter is uniform and glossy.
Prepare for baking: Wrap the outside of the springform pan with a double layer of foil to prevent leaks if using a water bath. Set the pan inside a larger roasting pan.
Bake with gentle heat: Pour the filling over the crust.
Add about 1 inch of hot water to the roasting pan to create a water bath. Bake for 40–50 minutes. The edges should be set, and the center should jiggle like gelatin, not slosh.
Cool gradually: Turn off the oven, crack the door, and let the cheesecake sit inside for 45 minutes.
This slow cooldown helps prevent cracks.
Chill completely: Remove the pan from the water bath. Run a thin knife around the rim to release the sides. Cool to room temperature, then cover and chill for at least 6 hours, preferably overnight.
Serve: Release the springform ring.
Slice with a hot knife wiped clean between cuts. Add berries or a light topping if you like.