Preheat your oven to 350°F (175°C). Grease your baking pan and set aside.
Place sliced apples in a mixing bowl with half of the sugar and a pinch of salt, then toss gently to coat.
In a separate bowl, whisk together the flour, ground cardamom, baking powder, and remaining salt until well combined.
In a larger bowl, beat together the eggs, vanilla, melted butter, and sugar until the mixture is smooth and slightly fluffy, about 2-3 minutes.
Fold the dry ingredients into the wet mixture gradually, mixing just until combined to keep the batter light.
Gently fold the apple slices into the batter, distributing evenly without overmixing.
Pour the batter into your prepared baking pan, smoothing the top with a spatula.
To make the crumble topping, combine the remaining flour, chopped almonds, remaining sugar, and a few small pieces of cold butter. Use your fingers or a pastry cutter to mix until coarse crumbs form.
Sprinkle the almond crumble evenly over the batter, pressing gently to adhere.
Bake in the preheated oven for 45-50 minutes, or until the top is golden brown and a toothpick inserted in the center comes out clean.
Remove the cake from the oven and let it cool in the pan for about 10 minutes, then transfer to a wire rack to cool completely.
Slice the cake once cooled and enjoy the fragrant, layered textures of tender apples, spiced crumb, and crunchy topping.
