Place pecans in a single layer on a baking sheet. Bake at 350° for about 10 minutes or till lightly browned and fragrant. Let cool. Arrange in clusters of 3-4 on silicone liners or parchment paper.

Combine butter, brown sugar, corn syrup, and salt in a 6 quart pot. Bring to a boil over medium heat. Add the sweetened condensed milk and vanilla.

Continue cooking and stirring till mixture reaches 235-240 degrees. I like to use the ice water test, it's more accurate. Drop a small spoonful of the hot caramel into a bowl of ice water. When you take it out, you should be able to roll it into a ball. Then it's done.

Quickly spoon the caramel over the pecan clusters, making sure caramel is touching each of the pecans. Let sit to harden.

Melt the chocolate chips and oil in the microwave at half power, stirring often till smooth. Spoon chocolate on top of each layer of caramel. Let sit for 1-2 hours, or till hardened.