Preheat oven to 350°F. Grease a 10×15 jelly roll pan.
In a large bowl, mix flour, sugar, salt, and baking soda.
In a saucepan, combine butter, oil, cocoa powder, and water. Bring to a light boil.
Pour hot mixture into dry ingredients and mix gently.
Add buttermilk, eggs, and vanilla. Stir until smooth.
Pour batter into pan and bake 20–23 minutes.
During the last 5 minutes, melt butter, cocoa powder, and milk for the frosting.
Remove from heat, whisk in powdered sugar and vanilla.
Pour warm frosting over hot cake.
Add pecans, chocolate chips, and a caramel drizzle.
Cool before slicing, or serve warm.