Step 1: Preheat oven to 350°F (175°C). Line an 8x8 inch (20x20 cm) baking pan with parchment paper, leaving an overhang on the sides for easy removal.
Step 2: In a medium bowl, combine the crushed cookies, melted butter, and granulated sugar. Mix until well combined.
Step 3: Press the cookie mixture evenly into the bottom of the prepared baking pan. Bake for 10-12 minutes, or until lightly golden. Let the crust cool completely on a wire rack.
Step 4: While the crust cools, prepare the filling. In a large bowl, combine the thoroughly drained ricotta cheese, powdered sugar, vanilla extract, cinnamon, and salt. Beat with an electric mixer on medium speed until smooth and creamy.
Step 5: Gently fold in the mini chocolate chips until evenly distributed.
Step 6: Once the crust is completely cool, spread the ricotta filling evenly over the crust.
Step 7: Cover the pan loosely with plastic wrap and refrigerate for at least 4 hours, or preferably overnight, to allow the filling to set properly.
Step 8: Before serving, use the parchment paper overhang to lift the entire block of squares out of the pan onto a cutting board. Cut into 12-16 squares.
Step 9: Garnish with an extra dusting of powdered sugar, chocolate shavings, or chopped pistachios, if desired, and serve chilled.