Make & cool the raspberry sauce by mixing 1 teaspoon water with cornstarch in a small bowl. Combine raspberries, sugar, and remaining water in a saucepan. Cook until simmering, then add cornstarch mixture. Simmer for 3 minutes, strain to remove seeds, and cool completely.

Preheat oven to 350°F (177°C). Line a 9-inch square baking pan with parchment paper. Pulse Oreos in a food processor to fine crumbs. Combine with melted butter and press into pan. Bake for 8 minutes.

Melt white chocolate in a double boiler or microwave. Cool slightly. Beat cream cheese and sugar until smooth. Add flour, lemon juice, vanilla, and salt, then mix in eggs one at a time. Add cooled white chocolate and mix until just combined.

Pour half of the filling into the crust, drizzle half of raspberry sauce over it, then spread remaining filling on top, drizzling remaining raspberry sauce before swirling gently.

Bake for 32-36 minutes until set. Cool for 45 minutes and chill in the refrigerator for at least 3 hours before slicing.

Lift the bars out using parchment overhang and cut into squares. Store leftovers in the refrigerator.