How to Make It
Preheat oven to 325°F. Lightly coat a 10-inch cast-iron skillet with cooking spray. Beat brown sugar, granulated sugar, and butter with a heavy-duty electric stand mixer at medium speed until light and fluffy. Add egg, milk, and vanilla, beating until blended.
Whisk together flour, baking soda, and salt in a bowl. Add to butter mixture gradually, beating at low speed until combined.
Add chopped pecans and toffee bits; beat until combined.
Spread mixture evenly in prepared skillet. Top with pecan halves and caramel sauce.
Bake in preheated oven until golden and set, about 50 minutes. Let stand 15 minutes; sprinkle with sea salt and cut into wedges. Serve with vanilla ice cream.