Pre-heat oven to 350F (180C). Grease and flour an 8 or 9 inch cake pan (I used an 8 inch).
In a medium bowl whisk together the flour, baking powder, baking soda and salt. Set aside.
In the mixing bowl beat the sugar and vegetable oil until light 2-3 minutes. Add the eggs and yolk 1 at a time, beat to combine after each addition. Add the yogurt, milk and vanilla, beat 2 minutes. Add the dry ingredient in 3 additions. Beat 1 minute.
Spread ½ the batter* in the prepared cake pan, bake 15 minutes, remove and spread the jam on top, carefully spread the remaining batter on top of the jam and continue to bake for 30-35 minutes or until a toothpick comes out clean or with a few crumbs attached. Let cool in pan 15-20 minutes then move to a wire rack to cool completely. Dust with powdered sugar before serving. Enjoy!
*I just eyed it and as you can see from the photos I was a bit off, if you want it even then you will have to measure or weigh the batter.
Notes
To make your own cake flour, for every cup of all purpose flour remove 2 tablespoons and replace with corn starch. Sift the ingredients together to remove any lumps.You can substitute the vegetable oil with 1/2 cup soft butter.Once the cake is cool, you can cover it well with plastic wrap or place in an airtight container, it will keep at room temperature for up to 2 days, or refrigerate for up to a week. Bring to room temperature before serving.You can freeze it, too. Wrap it tightly in plastic wrap and store it in a large freezer bag or airtight container. It will keep in the freezer for up to two months.