Preheat oven to 350º.
Coarsely chop 1 cup cashews; set aside. Process remaining 1 ½ cups cashews in a food processor until finely chopped. Pour in oil. Process until mixture is creamy, about 2 minutes. (About 45 seconds in the Blendtec Twister Jar.)
Put cashew mixture, butter, and sugars in the bowl of an electric mixer fitted with the paddle attachment; mix on medium speed until fluffy, about 2 minutes. Mix in egg and vanilla.
Mix flour and salt together. On low speed gradually add flour mixture to wet ingredients. Mix in chopped cashews. (Save some to decorate tops of cookies, if desired.)
Drop one tablespoon dough (I used a #50 scoop) into each cup of a greased mini muffin tin. Bake 10 to 12 minutes until edges are browned, and centers are firm. Remove the cookies from the oven and using the end of a thick-handled wooden spoon make a small, deep well in the center of each cookie.
Put the caramel and milk in a microwave safe bowl. Cook on high for 1 minute. Stir. Cook on 50% power for 1 minute or until caramel starts to bubble. Stir again. Repeat until caramel is melted and combined with milk.
Fill the center of each cookie with the melted caramel. Sprinkle chopped cashews on top if desired.
Remove the cookies to a wire rack to cool. Store in airtight container in single layer.