CITRUS UPSIDE DOWN CAKE

 From CM, from Karen Sanchez-Eppler, also via epicurious, halved to fit into a 6" cake pan

Ingredients:

Upside down layer

1 large unwaxed lemon, sliced very thinly on a mandoline

50g + 1 T sugar

56.5g (1/2 stick) unsalted butter

1 T lemon juice

Cake Batter (quartered, as reviews said the batter amount was too generous)

78 g AP flour

1/4 t baking powder

1/8 t baking soda

1/8 t kosher salt

1 small egg, or 1/2 large egg

59 g, or 1/4 c olive oil

57 g, or 1/4 c greek yoghurt

50 g sugar

Lemon zest from remaining lemon, if any

1/8 t lemon extract

1/8 t vanilla extract

Methodology:

Preheat oven to 350°F, and butter a 6" cake pan. 

Slice the lemon and toss with 1 T sugar in a bowl.  Reserve.  Zest the rest of the lemon, and juice it.   Toss the zest with the 50 g of sugar for the cake batter.  Reserve zest and juice separately.

Melt the butter.  Remove from heat and whisk in the 50 g sugar, and 1 T lemon juice.

Whisk the mixture until the sugar dissolves and the mixture is glossy and thickened a little. Pour the melted butter and sugar into the prepared cake pan and smooth into an even layer to cover the bottom.  Arrange the lemon slices, overlapping slightly, in the pan.  Place the cake pan in the freezer until the butter and sugar layer solidifies.

In the meantime, whisk the flour, baking powder, baking soda, and salt in a large bowl.  Whisk the egg with the olive oil in another large bowl until well combined.  Add the yogurt, sugar, zest and extracts. Make a well in the flour mixture and add the wet mixture in three additions, folding in each addition until no dry bits of flour remain. 

Pour the cake batter over the solidified butter/sugar mixture in the cake pan, and place in the oven, atop a rimmed baking sheet.  Bake for 30 minutes.  A toothpick should come out mostly clean, with no raw batter clinging to it.  Transfer to a wire cooling rack and let cool for 15 minutes. Invert the cake onto a serving plate and scrape any remaining lemon syrup out of the pan with a spatula.  Allow the cake to cool for 1 hour more before serving.