1. Preheat oven to 350 degrees F. Place 1-1/2 cups of the cashews in a food processor; cover and process until finely chopped. Gradually add oil, processing about 2 minutes or until mixture is as creamy as peanut butter. Coarsely chop the remainder of the 2-1/4 cups cashews; set aside.
2. In a large bowl, combine the processed cashews, brown sugar, butter, and the 1/3 cup granulated sugar. Beat with an electric mixer on medium to high speed until light and fluffy, scraping side of bowl occasionally. Beat in egg and vanilla until combined. Gradually add flour, beating on low speed until combined. Stir in the coarsely chopped cashews.
3. Shape dough into 1-1/2-inch balls. Place 2 inches apart on an ungreased cookie sheet. Dip the bottom of a glass in additional granulated sugar and flatten each ball to about 3/8-inch thickness.
4. Bake for 10 to 12 minutes or until bottoms are light golden brown and edges are firm. Cool cookies on a wire rack.
5. For topping: In a small saucepan, combine caramels and whipping cream. Cook and stir over low heat until caramels are melted and mixture is smooth. Cool slightly (10 to 15 minutes). Spoon a small amount of icing on top of each cookie; add a cashew half. Let stand for 30 to 60 minutes or until icing is set. Makes about 36 cookies.
6. To Store: Layer uniced cookies between waxed paper in an airtight container; cover. Store at room temperature for up to 3 days or freeze for up to 3 months. To serve, thaw cookies if frozen. Prepare icing and decorate cookies as directed in step 5.