Preheat the air fryer to 350°F for 3 minutes so the basket is hot before adding the apples.

While the air fryer preheats, core the apples and slice them into 1/2 inch thick wedges, keeping the pieces as even as possible.

In a large bowl, combine the melted butter, brown sugar, cinnamon, vanilla bean paste, nutmeg, and salt, and stir until the mixture is smooth.

Add the apple slices to the bowl and toss until every piece is lightly and evenly coated, without excess liquid pooling in the bottom.

Lightly spray the air fryer basket with nonstick cooking spray if needed, then arrange the coated apples in a mostly single layer with only slight overlap.

Air fry the apples at 350°F for 10 to 12 minutes, shaking the basket halfway through cooking to promote even browning and prevent sticking.

Around the 8 minute mark, check one of the thicker slices with a fork; it should be tender in the center with deep golden, caramelized edges.

Continue cooking, checking once more near the end, until the apples look glossy and lightly caramelized and smell fragrant.

Remove the basket from the air fryer and let the apples rest for 2 to 3 minutes so the hot syrup thickens and clings to the slices before serving warm.