Biscuits: Preheat oven to 425 degrees. Coat baking sheet with nonstick cooking spray.
In large bowl, mix flour, sugar, baking powder, baking soda, salt and lemon rind. In small bowl, mix buttermilk and oil. Add to flour mixture, stirring with fork just until mixture comes together. (Mixture will be lumpy; do not overmix.)
Sprinkle work surface with flour. Turn out biscuit dough and with lightly floured hands pat dough into a 7-inch circle, about 1/2 inch thick. Use a 2 3/4-inch star or biscuit cutter, cut out biscuits, gathering up scraps. Transfer to prepared baking sheet. Bake until golden brown on top and bottom, 10 to 12 minutes.
Meanwhile, in food processor, purée strawberries with sugar. Transfer to saucepan and bring to boil over medium heat, stirring often. Reduce heat to low and cook 3 minutes. Transfer to bowl to cool.
To assemble, split biscuits in half with fork or with sharp, serrated knife. Place bottom half of biscuit on dessert plate. Cover lightly with some strawberry sauce. Add 1/4 cup raspberries. Top with 2 tablespoons whipped cream if desired. Cover with biscuit top. Surround shortcake with a ring of strawberry sauce. Top biscuit with 1 teaspoon whipped cream if desired, and a single raspberry. Repeat with remaining shortcakes.