Line an 8 X 8-inch baking pan with foil. Let two sides of the foil overhang on the baking dish so it will be easier to pull out the finished cheesecake.
Pulse the cookies in a food processor until they are finely ground. Add the melted butter and pulse until the cookies are moistened. ( Or, if you don't have a food processor, place in a large baggie and crush with a rolling pin ...then add butter and stir till well combined)
3Transfer the ground Oreos to the prepared baking pan, and press the crumbs into an even layer on the bottom of the pan. Bake for 10 minutes.
4In the bowl, beat the cream cheese on medium high until light and smooth, about 2 minutes.
Mix in the sugar until well combined.
Blend in the sour cream, vanilla, and salt.
Beat in the egg and egg yolk until well blended in.
5Gently stir in the chopped oreos ( make sure the chopped cookies are roughly chopped). You don't want them fine, as I said I chop into fourths.
6Pour the cheesecake batter over the prepared crust; smooth the top with a spatula. Bake for 40 minutes or until cheesecake is set around the edges but slightly wobbly in the center.
7Cool to room temperature for about 1 hour; cover the pan and refrigerate until well chilled, overnight is best.
Cutting the bars:
Lift the overhang ends of the foil from the pan, and place the cheesecake on a cutting board or nice flat surface. Peel away the foil and slice into bars. Clean the knife blade after each slice to keep the edges nice. Also, pull knife upward rather than sliding it out after the cut to keep the edges clean.
8Melt the chocolate in separate bowls in the microwave in 30 second increments, stirring frequently, until completely melted.
I then get a small baggie, roll the top down, pour in the chocolate. Snip a small hole on one corner of the bag. Squeeze and drizzle over the Cheesecake bars.