Preheat the oven to 350°F and line baking sheets with parchment paper or a silicone mat. Also, prepare a small glass with ice and water in order to have very cold ice water to pull the dough together.
In a large bowl, cream the butter and sugar together with a hand mixer. Add flour, salt, and vanilla, and continue mixing. Next, add the prepared ice water to help combine everything. The dough will be very crumbly at this point, don't panic
Take about 2 tablespoons of dough and use your hands to roll it into a ball about 1-1½ inches around. Place the ball on the prepared cookie sheet and flatten it to about ½ inch thick with a glass or something flat.
Bake for 12-14 minutes, remove the cookies from the oven when they are just starting to brown on the edges. Immediately remove the cookies from the pan and cool on a wire rack.
Combine the unwrapped caramels and evaporated milk in a microwave-safe bowl and melt at 20-30 second intervals, stirring in between, until smooth and creamy. Be careful, it's hot!
Spread the melted caramel over each cooled cookie with a spoon and let it set completely.
Place the chocolate chips in another microwave-safe bowl and cook in the microwave for two 20-30 second intervals, stirring in between. Stir in the vegetable oil and then heat in the microwave for one more interval. Stir until completely melted and smooth. Spread the chocolate on top of the cooled caramel with a spoon.
Let the chocolate set in the fridge for about 10 minutes before digging in.