Make the crust: Preheat the oven to 350°F. Line the bottom of a 9-inch square pan with a sheet of parchment paper long enough to hang over the sides by 1 inch.

Pulse the Oreos and salt in a food processor until finely ground. Add the melted butter and pulse until the mixture resembles wet sand.

Transfer the mixture to the baking pan, pressing it into an even layer (I like to use the bottom of a flat measuring cup for this). Bake until the crust is just set and fragrant, about 10 minutes.

Make the filling: Combine the cream cheese and sugar in the bowl of a stand mixer fitted with the paddle attachment. Beat on medium speed until smooth, about 1 minute. Scrape down the sides of the bowl, then add the tahini, sour cream, vanilla, and salt, and beat until just combined. Scrape down the sides of the bowl again. Add the eggs, one at a time, beating after each addition, until the mixture is smooth. Pour the filling into the crust and smooth into an even layer.

Bake until the filling is just set but has a slight jiggle in the center, 20 to 25 minutes. Place on a wire rack and let cool completely. Refrigerate for at least 4 hours or up to overnight.

Make the ganache: Place the chocolate chips in a medium heatproof bowl. Heat the heavy cream in a small pot over medium-high heat until it begins to simmer. Pour the cream over the chocolate chips and let sit for 2 minutes, then whisk until smooth and glossy.

Pour the ganache over the cheesecake in an even layer. Let sit at room temperature until the chocolate begins to firm up, about 20 minutes. Sprinkle the chocolate ganache with sesame seeds and flaky salt. Refrigerate until set, at least 1 hour or up to overnight.

When ready to serve, use the overhanging parchment paper as handles to carefully lift the bars from the baking dish and set them on a cutting board. Cut into bars.