Preheat oven to 350°F (180°C). Butter two 8-inch baking dishes and line bottoms with parchment paper, leaving an overhang. Place dishes on a cookie sheet.
In a saucepan, combine sugar, Scotch, water, and corn syrup. Bring to a boil over medium heat. Cook until golden amber. Remove from heat and stir in cream and butter. Return to heat until smooth. Divide sauce between pans and top with pecan halves.
In a bowl, whisk flour, chopped pecans, baking soda, and salt. In another bowl, beat butter, oil, and brown sugar until fluffy. Add vanilla and eggs one at a time. Gradually add flour mixture, alternating with buttermilk, until combined.
Pour batter evenly over caramel in pans. Bake for 40–45 minutes, or until a toothpick inserted in the center comes out clean.
Cool 10–15 minutes, then carefully invert onto serving plates.
