Preheat oven to 325°F (170°C).

Reserve 16 cookies, and crush the rest into fine crumbs. Mix the crushed cookies with 1/4 cup of the sugar, and the margarine. Press firmly into the bottom of a nine-inch spring-form pan (use a silver spring-form pan, not a dark, nonstick pan).

Stand remaining 16 cookies around edge of pan, rounded side facing outward, and cookies touching one another, to achieve a scalloped effect. Press cookies gently into crust around edge of pan to secure.

Beat cream cheese and sugar in a large bowl on medium speed until well blended.

Add sour cream and vanilla; mix well.

Add eggs, one at a time, beating on low speed after each addition, just until blended. Pour into prepared crust.

Bake 45 to 50 minutes or until center is almost set.

Run a small knife around rim of pan to loosen cake, but let the cake cool before removing rim from the pan. Refrigerate 4 hours or overnight.

For an optional topping, pour one-half to three-fourths of the jar of Dulce de Leche caramel onto the center of the cheesecake and smooth. Top with pecan pieces, if desired.