Preheat oven to 350°F. Line a 9×13-inch pan with parchment, leaving overhang; lightly grease.
Whisk flour, powdered sugar, salt, and about 1 tsp lemon zest in a large bowl.
Cut in the cold butter with a pastry cutter or fingers until sandy and clumping.
Press crumbs firmly into the pan in an even layer. Dock lightly with a fork.
Bake the crust 15–18 minutes, until the edges are lightly golden. Leave oven on.
Beat cream cheese in a mixing bowl until smooth and fluffy, 1–2 minutes.
Blend in sweetened condensed milk until silky and no lumps remain.
Whisk cornstarch into lemon juice until dissolved. Add to bowl with remaining zest and vanilla; mix until smooth.
Pour filling over the hot crust and smooth the top with a spatula.
Bake 18–22 minutes, until the center has a slight jiggle and edges look set.
Cool in the pan 1 hour, then refrigerate at least 2 hours until firm.
Dust with powdered sugar. Slice into bars and top with whipped cream if desired.
Notes
Variation: Swirl 2–3 tablespoons lemon curd into the filling before baking for extra tang. For a coconut twist, replace 1/2 cup flour in the crust with fine unsweetened shredded coconut. Storage: Keep bars chilled in an airtight container for up to 4 days; freeze, well wrapped, for up to 2 months.This recipe is an original creation inspired by classic Creamy Lemon Dream Bars flavors. All ingredient ratios and instructions are independently developed.