Preheat the oven to 350 degrees. Butter and flour a 9 inch round baking pan.
For the topping:
Combine the sugar, brown sugar, cinnamon and nutmeg in a bowl. Stir in the melted butter and then the flour. Mix well and set aside.
For the cake:
Cream the butter and sugar in a bowl for 5 minutes until light. Add the eggs 1 at a time, then add the vanilla, lemon zest, and sour cream. In a separate bowl, sift together flour, baking powder, baking soda, and salt. Add the flour mixture to the batter until just combined. If you are using fresh berries, fold them in. Spoon the batter into the prepared pan and spread it out evenly. Pour the topping evenly over the batter and bake for 40 to 50 minutes until golden brown.