A light citrus vanilla cake
Preheat the oven to 325 degrees.
Grease a 9 inch cake pan generously with butter. Refrigerate the pan while you prepare the batter.
Slice the orange into thin slices. Set aside.
In a stand mixer, fitted with the paddle attachment, beat the eggs, sugar and orange zest on medium speed until light and fluffy (3 to 4 minutes).
Turn the mixer speed down to low. Add the oil a little bit at a time.
Add the vanilla and yogurt. Mix until incorporated.
In a separate bowl, mix the dry ingredients together.
Add the dry ingredients to the wet ingredients. Mix just until incorporated on low speed.
Arrange the orange slices any way you like on the bottom of the greased pan. Brush one side of the orange slices (the side that isn't touching the bottom of the pan) with one tbsp of the orange liqueur.
Pour the batter into the pan slowly. Make sure that the space between the oranges is completely covered with cake batter.
Bake at 325 degrees in the centre of the oven for approximately 40 minutes or until a toothpick comes out clean.
Allow the cake to cool for 15 minutes. Shake the pan from side to side gently to determine whether the cake has cooled enough to release itself from the pan. If not, allow the cake to cool 5 more minutes and check again.
Put a plate over the the cake pan and flip the cake.
Brush the top of the cake gently with the orange liqueur. Brush the orange slices last (if you used blood oranges) so that there's no colour transfer onto the cake.