For the cake: Butter and flour a 9-inch cake pan. For best results, cut out parchment paper to fit the bottom of the pan. Place a dab of butter on the pan to hold the parchment in place and proceed to butter and flour the parchment and the sides of the pan.
Preheat the oven to 350 degrees F. Set a rack in the lower third of the oven. Sift together the flour, Clabber Girl Baking Powder, baking soda and salt. Set aside.
Using a stand mixer or hand held beaters, cream the butter for about one minute and pour in the fruit juice concentrate. The mixture may look curdled or lumpy, it's okay. Stop and scrape the sides of the workbowl and beneath the beaters several times throughout the mixing process to ensure even mixing. Pour the beaten egg very slowly to incorporate. Add the vanilla. Set the speed on low and alternately add the flour mixture in three parts and the milk in two parts, beginning and ending with the flour. Stop and scrape the bowl in between additions to assure it is evenly mixed, increasing the speed briefly after each addition till smooth and creamy. Increase the speed at the end for about 20 seconds.
Fold in 1 1/2 tablespoons of the lemon zest and poppy seeds, if using. Spread the batter evenly in the prepared pan and smooth the top. Bake for about 35 to 40 minutes or until a wire cake tester pressed in the center comes out clean.
Allow the cake to cool for about 15 to 20 minutes and invert from the pan to finish cooling on a wire rack.
For the Mascarpone Cream glaze: Place the Mascarpone in a small bowl and whisk in the fruit juice concentrate and lemon juice. Refrigerate the glaze until ready to use. If the lemon juice separates from the cheese, simply whisk it back in and refrigerate a little longer. To glaze and serve the cake: Spread the cake with the glaze in swirling patterns over the top and sides. Garnish with the reserved lemon zest and raspberries, if you like. Serve at room temperature or store, covered, at room temperature. This cake is at its best served the day it is made.
* regular cream cheese may be substituted.
Recipe by Mani Niall - Mix it up with Mani