Prep Pan & Oven
Preheat oven to 325°F (165°C). Wrap a 9-inch springform pan in 2–3 layers of heavy-duty foil (or use a silicone water-bath wrap). Boil water for the water bath.

Make the Brownie Crust
Whisk melted butter with granulated and brown sugars until glossy. Beat in eggs and vanilla. Sift in cocoa, flour, salt, and espresso powder; fold just until no dry streaks remain. Stir in mini chips if using. Spread into the pan and bake 15–18 minutes—edges set, center soft. Cool 10 minutes.

Cook the Caramel
Heat sugar in a heavy saucepan over medium, stirring occasionally until melted and deep amber. Whisk in butter (it will bubble), then slowly stream in warm cream and whisk smooth. Off heat, stir in salt. Cool 15–20 minutes until thick-but-pourable.

Mix the Cheesecake Filling (low-air)
On low speed, beat cream cheese until completely smooth. Add both sugars; mix until silky. Blend in sour cream, heavy cream, vanilla, and cornstarch. Add eggs one at a time on low, mixing only until each disappears.

Assemble
Pour half the filling over the brownie crust. Drizzle ¼–⅓ cup caramel in thin lines; swirl lightly with a skewer. Add remaining filling and tap the pan to release bubbles. Spoon a few thin caramel ribbons on top and lightly swirl.

Bake in Water Bath
Set the springform inside a deep roasting pan. Pour hot water into the roasting pan to reach halfway up the springform sides. Bake 55–65 minutes until edges are set and the center still has a gentle wobble (or 150–155°F / 65–68°C internal).

Gentle Cooldown
Turn off the oven, crack the door, and let cheesecake rest 45 minutes in the warm oven to minimize cracks.

Chill Fully
Remove from water bath; discard foil. Run a thin knife around the rim. Cool to room temperature, cover, and chill 6–8 hours (overnight is best).

Finish & Serve
Release the ring and transfer to a platter. Top with brownie chunks, mini chips, and warm caramel. Sprinkle flaky salt. Slice with a hot, clean knife.