Preheat the oven to 325 degrees F or 160 degrees Fahrenheit. Lightly grease the bottom of 2 9-inch pans with butter or canola oil, then line the bottom of each pan with parchment or baking paper. Leave the sides of the pan ungreased.
In a large bowl, sift together the flour, 1¼ cup sugar, salt, baking powder twice. In a separate, medium-sized bowl, beat the egg yolks, lemon zest, oil, water, and vanilla on high speed until smooth. Stir this mixture into the flour mixture.
In a separate bowl, whisk together the egg whites until soft peaks form, then add ¼ cup sugar and continue whisking until stiff peaks form and the egg whites are glossy.
Using a large spoon, scoop out a large scoop of the egg whites and stir quickly into the batter. Then, gradually fold the remaining egg whites into the batter until all of the egg whites are incorporated, but do not over mix. Pour the batter into the prepared pans and bake for at least 40-45 minutes. Check the cakes by gently pressing them with your finger; the top should spring back and should be golden brown (you can double check by inserting a toothpick in the center to see if it comes out clean).
Remove the cakes and set them on wire racks to cool for at least an hour. While the cakes are cooling, make the mascarpone icing. In a large bowl, whip the whipping cream and confectioners sugar together until soft peaks form, then add the vanilla. Run a spoon through the mascarpone to break it up a little, then add it to the whipped cream and beat again until it's thick and spreadable. Add the lemon curd and swirl through with a spatula.
To assemble the cake, use a serrated cake knife to cut the top off the layers to make even layers. Use a spatula to spread a thick layer of icing on the top of one layer, then sprinkle the top with raspberries. Add the second layer on top and then spread icing all over the top and sides of the cake. Decorate with the remaining raspberries. Refrigerate this cake until it's time to serve.
Recipe by Grits and Chopsticks at https://www.gritsandchopsticks.com/the-gravy-train/2018/06/raspberry-and-lemon-curd-chiffon-cake.html