Lemon Upside-Down Cake

Directions

1. 1
   Preheat the oven to 350.
2. 2
   Set a 9-inch nonstick cake pan over moderate heat.
3. 3
   Add 4 tablespoons of the butter and when it is melted, stir in the brown sugar until dissolved, about 1 minute.
4. 4
   Remove from the heat.
5. 5
   Arrange the lemon slices in the melted brown sugar.
6. 6
   In a medium bowl, whisk the flour with the baking powder and salt.
7. 7
   In a large bowl, with an electric mixer, beat the remaining 8 tablespoons of butter with the granulated sugar until light and fluffy.
8. 8
   Beat in the vanilla and the egg yolks, one at a time.
9. 9
   At low speed, beat in the dry ingredients in 3 batches, alternating with the milk.
10. 10
    In a stainless steel bowl, beat the egg whites with the cream of tartar at high speed until firm peaks form.
11. 11
    Fold one-third of the beaten whites into the batter, then fold in the rest.
12. 12
    Scrape the batter into the prepared pan and bake for about 30 minutes, or until a toothpick inserted in the center of the cake comes out clean.
13. 13
    Let cool in the pan for 15 minutes, then invert it onto a plate.
14. 14
    Serve warm or at room temperature with whipped cream.