Preheat your oven to 350°F.
Cream together the butter and sugar.
Add yogurt, lemon zest, and eggs one at a time and mix until smooth.
In a separate bowl, whisk your flour, baking powder, and salt.
Whisk your milk and extract in a separate jug.
Add ⅓ of the dry mixture to the butter mixture and mix to combine.
Add ½ the milk mixture and mix to combine.
Repeat until both the dry and milk mixtures are all incorporated (making sure to finish on the dry mixture).
Fold in the poppyseeds.
Grease an 8" pan (I used springform) with nonstick cooking spray and line with a parchment round.
In a small sauce pan add the sugar and water.
Turn the stove on medium heat, swirling the pan constantly until a light medium shade of amber is reached.
Place your lemon slices down onto the greased, parchment lined pan.
Pour the caramel over top.
Scoop the batter over the oranges and spread out to form an even layer.
Bake the upside down cake in the preheated oven for 25-30 minutes or until the top springs back to the touch.
When the cake comes out of the oven, run through the sides of the pan with an offset spatula to release the edges.
Let the cake cool for 10 minutes, and then invert it onto a serving plate.
