1. Preheat the oven to 350°F (175°C). Grease a 9-inch round cake pan or springform pan and line the bottom with parchment paper.

2. Peel, core, and thinly slice the apples. Toss them with the lemon juice and ground cinnamon until evenly coated, then set aside.

3. In a medium bowl, whisk together the all-purpose flour, baking powder, and fine sea salt until well combined.

4. In a large mixing bowl, whisk the melted butter and granulated sugar until glossy and slightly thickened. Add the eggs one at a time, whisking well after each addition, then whisk in the vanilla extract.

5. Add the dry ingredients to the wet ingredients in two additions, alternating with the milk, stirring gently after each addition just until a smooth batter forms with no dry streaks.

6. Fold most of the cinnamon-coated apple slices into the batter, reserving a handful of slices for the top of the cake.

7. Pour the batter into the prepared pan and smooth the top. Arrange the reserved apple slices decoratively over the surface, then sprinkle with sliced almonds and the coarse or granulated sugar.

8. Bake for 35 to 45 minutes, or until the cake is golden brown and a toothpick inserted into the center comes out with a few moist crumbs but no wet batter.

9. Let the cake cool in the pan for 10 to 15 minutes, then run a knife around the edge and carefully transfer it to a wire rack to cool further.

10. Dust the cooled or slightly warm cake with powdered sugar if using, slice, and serve.