Prepare an 8-inch springform cake pan using a round piece of parchment paper on the bottom and baking spray on the sides. I used a 6-inch pan (not a springform) and I also sprayed the parchment paper to ensure the cake comes out in one piece.
In a small bowl combine all dry ingredients and set aside. With an electric mixer, beat together butter and sugar until fluffy and creamy. Add eggs and mix on medium speed until combined and smooth. Alternating and 1/3 at the time mix in dry ingredients, yogurt and jam.
. Pour batter into cake pan and bake on 350 degrees Fahrenheit for 40-45 minutes, or until a toothpick comes out clean. Remove the cake from the oven and allow to cool for 10 minutes. Remove cake from the pan and finish cooling on cooling rack. Once the cake has cooled, use the serrated knife to cut off the cake dome, then cut the cake in two, or three if you baked it in 6-inch pan, even layers.
In a small sauce pan bring heavy cream to boil over medium-low. Remove pan from heat and add white chocolate chips. Whisk until mixture is smooth, and then cool to room temperature. Add lemon zest, lemon juice and Mascarpone cheese. If mixture is too stiff add heavy cream, one tablespoon at the time. Cover bowl with clear wrap and refrigerate for two hours or until set.
Spread the lemon filling over each cake layer. For a naked look, do not frost the entire cake. I placed a dark-chocolate covered cherry on the top of my cake but you can decorate as you desire. Store the cake in refrigerator for up to a week. Remove cake from the refrigerator 10-15 minutes before serving.