Preheat oven to 350 degrees. Rub the inside of an 9? springform pan with butter, then sprinkle with a little bit of sugar and swirl it around the pan to coat. Tap out excess.
Use a microplane grater to remove 2 packed teaspoons of zest from the blood oranges. Next, use a sharp knife to slice the top and bottom off each orange to reveal its flesh. Place cut side down, then run your knife down the sides to remove the peel and as much white pith as possible. Turn the peeled oranges on their sides and slice into rounds.
Whisk together the flour, baking powder, salt and almond flour in a bowl and set aside.
In a large bowl, cream 1 cup butter with ¾ cup sugar using a stand mixer or electric beater. Add the blood orange zest, scrape in seeds from the vanilla bean, and continue beating until light and fluffy, about 5 minutes.
Add eggs, one at a time, being sure the first egg is fully incorporated before adding the second. Add the lemon juice and beat until mixture is pale and fluffy, about 4 minutes more.Add the dry ingredients, a little at a time, while beating on low speed. Add the yogurt and stir until just combined.
Spoon the batter into the prepared pan, smooth the top, and arrange the blood orange slices over top in a pretty pattern. Sprinkle the remaining 2 tablespoons of sugar over top, avoiding the very outer edges. Bake for about 45 minutes to one hour, or until the oranges are lightly caramelized around the sides and the center is mostly set.
Allow the cake to cool completely before slicing and serving with dollops of Greek yogurt. I find it’s best served cold. Keep refrigerated.