Melt butter in large saucepot over medium-high heat. Add apples, sugar, cinnamon, extract and nutmeg. Cook the mixture for 8-10 minutes or until the apples are just tender-crisp, stirring occasionally to coat apples and cook evenly. Stir cornstarch with lemon juice and zest until combined. Add to apple mixture and stir to thoroughly coat apples.
For the Topping
In food processor, pulse flour, sugar, baking powder, lemon zest, baking soda, ginger and salt to combine. Add butter; pulse to cut in butter to pea-sized crumbs. Add buttermilk; pulse until dough just comes together. Dough will be slightly sticky and wet. Do not overmix.
Divide the filling between 8 each 10-ounce ramekins. Top each with topping. Bake on sheet tray at 425°F for 8-10 minutes or until topping begins to brown. Reduce oven temperature to 350°F. Bake 20-25 minutes longer or until filling is bubbling and topping is cooked through and browned. Remove and cool 15 minutes before serving. Serve warm with salted caramel drizzle and a sprinkle of coarse sea salt.
For the Salted Caramel Drizzle
Heat sugar and water in covered 4-quart heavy-bottomed saucepot to boiling over high heat. Heat cream and salt to simmering in small saucepot over medium heat; remove from heat and cover to keep hot.
Once sugar mixture comes to a boil, remove lid. Continue to boil for about 12-15 minutes or until the syrup is just starting to turn a light amber color. Reduce heat to medium-high and continue to cook about 8-10 minutes or until the syrup is a dark amber color and is just beginning to smoke, and candy thermometer reaches 350°F
Immediately remove caramel from heat and pour about ½ cup hot cream into sugar mixture allowing bubbles to diminish. Add remaining cream, again allowing bubbling to diminish.
Whisk in cold butter and cool. Caramel sauce can be made in advance and held up to 1 week under refrigeration. Reheat before serving in microwave or water bath until warm and fluid.