Heat the oven to 350°F. Spray a 9-inch round cake pan with cooking spray and line with parchment paper.
Mix flour, baking powder, and salt in a large bowl. Whisk the ricotta, 1 cup sugar, citrus zest, eggs, and vanilla in a medium basin until smooth.
Stir or fold the flour mixture until mixed. Fold in the melted butter, then half the raspberries, smashing them gently to create a streaky, tie-dyed effect.
Don't let them vanish into the batter. Spread remaining raspberries and ¼ cup sugar on top of the batter in the pan.
Bake 55–65 minutes until golden brown and a tester or toothpick put into the center comes out clean. Unmold after 20 minutes of cooling.
This cake can be cooked 3 days ahead, wrapped in plastic, and refrigerated at room temperature.
serving the cake with a bowl of sweetened or unsweetened ricotta.