• Preheat oven to 325F (160C).  Line a 13x9 baking pan with foil and set aside.
• To make the crust, place 25 of your Oreo cookies in a food processor and pulverize until they are fine crumbs.  Add butter and salt and pulverize again, until completely combined.
  40 Oreo cookies, 4 Tablespoons (55 g) butter, ¼ teaspoon salt
• Pour cookie crumb mixture into prepared baking pan and use the back of a spoon to press the crumbs firmly into an even layer.  Set aside.
• Break your remaining 15 Oreo cookies into pieces -- do not completely pulverize them but break them into fragments (to do this, I place the cookies in a large Ziploc bag and whack them a few times with a rolling pin).  Set aside.

Cheesecake Layer

• In a stand mixer (or in a large bowl with a hand-mixer), cream together softened cream cheese and sugar, scraping down the sides with a spatula occasionally to ensure ingredients are mixed well.
  32 oz (910 g) cream cheese, 1 cup (200 g) granulated sugar
• Add sour cream and stir well, pausing once to scrape down the sides and bottom of the bowl.
  ¾ cup (180 g) sour cream
• Add eggs, one at a time, beating until just mixed after each addition (and scraping down the sides after each addition)
  4 large eggs
• Stir in vanilla extract and then use a spatula to stir in cookie pieces.
  1 teaspoon vanilla extract
• Spread cheesecake batter evenly over prepared cookie crust. If desired, sprinkle a few additional Oreo pieces over the top of the cheesecake.
• Bake on 325F (160C) for 40 minutes, or until center is set (center should bounce back if lightly touched).
• Allow to cool to room temperature, and then place in refrigerator for at least 6 hours before cutting and serving.