Prep the pan and oven. Heat your oven to 350°F (175°C). Butter a 9-inch pie dish or similar baking dish.
Slice the apples. Peel, core, and slice the apples about 1/4-inch thick. You want even slices so they cook at the same pace.
Season the fruit. In a bowl, toss the apples with 2 tablespoons sugar, cinnamon, and lemon juice.
If using cardamom, add it here. Spread the apples evenly in the prepared dish.
Mix the dry ingredients. In a medium bowl, whisk together the flour, 3/4 cup sugar, baking powder, and salt.
Add the wet ingredients. Pour in the melted butter, add the egg and vanilla, and stir until a thick, smooth batter forms. It will be scoopable rather than pourable.
Top the apples. Dollop the batter over the apples, then use a spatula or back of a spoon to gently spread it.
It doesn’t need to be perfect; it will even out in the oven.
Bake. Place the dish on the middle rack and bake for 35–45 minutes, until the top is deep golden and crisp, and the fruit is bubbling around the edges. A few darker golden spots are fine.
Rest and serve. Let it cool for at least 10–15 minutes so the juices settle. Serve warm with a scoop of ice cream or a drizzle of vanilla sauce.