Preheat oven to 350 degrees. Butter cake pans, dust with flour, then tap out excess. Sift flour, baking soda, baking powder, and salt into a large bowl.Advertisement
Cream butter and 1 1/2 cups sugar with a mixer until pale and fluffy. Add yolks, 1 at a time, mixing well after each addition. Reduce mixer speed to low, and add flour mixture in 3 batches alternating with buttermilk, and ending with flour. Transfer batter to a medium bowl.
Whisk whites in a clean bowl with a mixer on medium-high until foamy. Slowly add remaining 1/2 cup sugar, whisking until soft peaks form. Fold whites mixture into batter in 2 additions, then fold in jam.
Pour batter into prepared pans. Bake cakes until light gold and testers inserted into centers come out clean. Let cool in pans on wire racks for 15 minutes. Run a knife around edge of cake to loosen, and invert cakes onto wire racks. Let cool.
Batter amounts and cooking times for 2-inch-deep round pans:
14-inch: 8 cups per layer (24 cups total), 55 to 60 minutes
12-inch: 6 cups per layer (18 cups total), 45 to 50 minutes
10-inch: 4 cups per layer (12 cups total), 40 to 45 minutes
8-inch: 3 cups per layer (9 cups total), 35-40 minutes