Preheat oven to 400 degrees Fahrenheit. Combine butter, calvados, and granulated sugar in a medium bowl.
Quarter and core apples; thinly slice cross-wise. Stir apples into calvados mixture.
Divide apples between six 5- to 6-ounce individual soufflé or custard cups. Place cups on a baking sheet. Bake 35 to 40 minutes, until bubbly and apples are softened. Cool 15 to 20 minutes.
Scoop dulce de leche over apples. Sprinkle with gingersnap crumbs. Serve with a whole cookie if desired.
Variations roasted pears: replace apples with firm-ripe Bartlett or Bosc pears. Roasted peaches: replace apples with peeled peaches and use peach or apricot brandy instead of calvados.