Prep the pan. Line the bottom of a 9-inch springform pan with parchment for easy removal. Lightly grease the sides if you’d like cleaner edges.
Make the crust. In a bowl, mix cookie crumbs, melted butter, sugar (if using), and a pinch of salt until the texture feels like wet sand.
Press firmly into the bottom and slightly up the sides of the pan. Use the flat bottom of a measuring cup to compact it well.
Chill the crust. Place the pan in the fridge for 15–20 minutes while you make the filling. A cold, firm crust keeps the slices neat.
Beat the cream cheese. In a large bowl, beat softened cream cheese with granulated sugar until completely smooth and glossy, about 2–3 minutes.
Scrape the bowl to avoid lumps.
Add flavor. Mix in sour cream, vanilla, lemon juice, and a pinch of salt. Beat until combined and silky.
Whip the cream. In a separate chilled bowl, whip the heavy cream and powdered sugar to stiff peaks. It should hold its shape and not slide off the whisk.
Fold it in. Gently fold the whipped cream into the cream cheese mixture in two to three additions.
Use a light hand to keep the mixture airy.
Stir in the toffee. Fold in 1 to 1 1/4 cups toffee bits. Save a handful for the top. Distribute them evenly so you get crunch in every bite.
Fill the pan. Spoon the filling over the chilled crust and smooth the top with an offset spatula.
Tap the pan gently on the counter to settle any air pockets.
Chill to set. Cover and refrigerate for at least 6 hours, preferably overnight. This step is essential for a clean slice and firm texture.
Finish and serve. Run a thin knife around the edge before releasing the springform. Top with more toffee bits, a drizzle of caramel or chocolate, and a sprinkle of flaky salt.
Slice with a warm, dry knife for sharp edges.