Preheat oven to 325°F. Line a 9×13-inch baking pan with foil, leaving an overhang to lift the bars out later, and spray the foil with nonstick cooking spray.

Make the crust: Place 30 Oreo cookies (including the filling) in a food processor and pulse to fine crumbs. (If you don’t have a food processor, place cookies in a heavy-duty zip-top bag and crush with a rolling pin.)

Transfer the cookie crumbs to a bowl and add 6 tablespoons melted unsalted butter. Stir until the crumbs are evenly moistened.

Press the crumb mixture firmly and evenly into the bottom of the prepared 9×13 pan (use the bottom of a measuring cup to compact). Bake the crust for 10 minutes. Remove the pan from the oven and let the crust cool on a wire rack for 20 minutes. Keep the oven set to 325°F.

While the crust cools, place a large rimmed baking sheet on the very bottom oven rack and carefully pour hot water into the rimmed sheet until it is about halfway full. Leave this in the oven while you bake the cheesecake to create a water bath.

Make the cheesecake filling: In a stand mixer fitted with the paddle attachment or with a hand mixer, beat the cream cheese (38-ounce packages, room temperature) on medium speed until smooth and free of lumps.

Add 1 1/2 cups granulated sugar, 1/4 cup (61 g) sour cream (room temperature), and 2 teaspoons vanilla extract. Beat until the mixture is smooth, scraping down the bowl as needed.

Add 1/4 cup (31 g) all-purpose flour and mix just until incorporated.

Add 3 large eggs (room temperature), one at a time, beating on low speed and scraping the bowl after each egg. Mix only until each egg is fully incorporated—do not overmix.

Stir in 1 cup of the mini chocolate chips (reserve the remaining 1/4 cup for the top).

Pour the cheesecake batter over the cooled crust and smooth the top. Sprinkle the reserved 1/4 cup mini chocolate chips evenly over the batter.

Place the 9×13 pan on an oven rack one position above the rimmed baking sheet of water and bake for 40–45 minutes, or until the edges are lightly browned and the center is mostly set but still has a slight jiggle.

Remove the pan from the oven and set it on a wire rack to cool at room temperature for 1 hour. After it reaches room temperature, cover and chill in the refrigerator for at least 4 hours (or overnight) before using the foil overhang to lift and slice the bars.