Prepare: Preheat the oven to 325°F (165°C). Grease an 8-inch square pan and line it with parchment paper.
Make the mango purée: Combine the mango purée and sugar in a small pot. Blend until smooth, then cook over medium heat for about 15 minutes, stirring often, until slightly thickened. Lower the heat once it starts bubbling. Let it cool.
Make the crust: Crush the graham crackers into fine crumbs using a food processor or a zip-top bag and rolling pin. Mix with the melted butter, brown sugar, and salt. Press firmly into the pan. Bake for 10 minutes, then let it cool.
Make the filling: Beat the cream cheese, ½ cup mango purée, sugar, flour or cornstarch, salt, and vanilla on medium-low until smooth. Add the eggs and mix just until combined. Do not overmix. Gently finish mixing with a spatula.
Assemble: Pour the filling over the cooled crust and smooth the top. Spoon small amounts of the remaining mango purée evenly over the filling. Drag a chopstick through the purée to create swirls.
Bake and chill: Bake for 30 to 32 minutes, until the center is set and no longer looks wet. Cool completely in the pan, uncovered, so trapped moisture doesn’t make the crust soggy. Refrigerate for at least 4 hours, or until firm. Slice and serve chilled.