Preheat your oven to 350ºF (180ºC) and prepare an 8 1/2 to 9-inch loaf pan by buttering it generously and lining the bottom with parchment paper.

In a large mixing bowl, combine the flour, sugar, baking powder, and salt. Whisk together until well blended.

Pour in the heavy cream and whole milk into your bowl of dry ingredients. Mix until smooth, then add in the eggs, melted butter, and vanilla extract, whisking until combined.

Peel, core, and slice the apples thinly using a mandolin or a chef's knife.

Gently fold the sliced apples into the custard mixture.

Layer the ingredients in the prepared loaf pan: start with one-third of the apple slices at the bottom, then pour half of the custard mixture over them, repeating with another layer of apples followed by the remaining custard.

Optional: Sprinkle a layer of brown sugar on top before baking.

Bake in the preheated oven for 40-45 minutes, until set and light golden.

Allow the cake to cool in the pan for 30 minutes before lifting it out and transferring it to a wire rack.

Slice gently with a serrated bread knife and serve warm or at room temperature.