Plan ahead: Soak ⅓ cup raisins in rum overnight for extra flavor. Grab 8 ounces stale white bread a day or two early and store it in your bread box.
Prepare your baking pan by greasing it with ½ Tablespoon butter and sprinkling with 2 Tablespoons breadcrumbs, tapping off any excess. If using a non-stick pan, just grease with unsalted butter and skip the breadcrumbs.
Make the milk mixture by whisking together 1 ⅔ cups whole milk, ⅔ cup heavy cream, ½ cup granulated sugar, 3 medium eggs, and ¼ teaspoon vanilla extract in a large bowl. For easier dipping, pour the mixture into a shallow bowl.
Slice the bread into pieces about ½ inch (1,5 cm) thick.
Peel and core 4 large apples, slice them thinly.
Dip the bread slices in the milk mixture, let them soak, and arrange them in the pan to form the bottom layer.
Layer the bread with sliced apples, sprinkle with 2 Tablespoons granulated sugar, raisins, and finish with a dusting of ½ teaspoon ground cinnamon.
Soak the remaining bread in the milk mixture and layer it over the apples. Drizzle any leftover milk mixture on top and gently press down with a fork.
Slice the cold ⅔ stick unsalted butter into thin pieces and evenly cover the surface of the Žemlovka with them.
Preheat the oven to
340 °F for fan-forced, or
370 °F for conventional upper and lower heat. Bake for 40 minutes until the surface is beautifully golden and crispy. Sprinkle with 2 Tablespoons powdered sugar before serving.