Heat your oven to 350°F. Lightly butter a small baking dish or two 8–10 ounce ramekins and place them on a rimmed baking sheet. I used an oval dish measured at 9” x 6” x 2” with a 1.1-quart capacity.

Melt 1 tablespoon butter in a small skillet over medium heat. Add the apples, brown sugar, flour, lemon juice, vanilla extract, cinnamon, nutmeg, salt, and water. Cook for 5 minutes, stirring gently, until the mixture looks glossy and the apple edges begin to bend while the centers remain firm.

Remove from the heat and add the apple filling into the baking dish.

In a small mixing bowl whisk together the flour, sugar, baking powder, and salt. Add the melted butter, milk, and vanilla. Stir just until no dry pockets remain; a few small lumps are fine. The mixture should be pourable but not runny or too thick. Add in an extra tablespoon of milk if needed.

Divide the batter evenly over the apples. Spread gently, leaving a few narrow gaps near the edges for steam and bubbling juices. Sprinkle with the optional cinnamon sugar.

Bake for 30- 40 minutes, rotating the pan once after about 20 minutes, until the filling bubbles at the edges and the topping is evenly golden and springy at the center. A toothpick in the topping should not show wet batter.

Cool for 10 minutes. Serve warm as is or with vanilla ice cream.