While this delectable cake is baking you will be glad that, busy as you are, you sensibly left five minutes in your day to get it into the oven. It fills the house with such a wonderful aroma.
Heat the oven to 375°F. Butter and flour a 9-inch springform pan, and set it aside.
Beat the butter and sugar in the bowl of a stand mixer until light and fluffy, about two minutes. Add the eggs, one at a time, beating to incorporate after each addition, and add the vanilla in there too.
Meanwhile, whisk together the flour, cornmeal, salt, baking powder, and nutmeg. Add the flour mixture to the batter in 3 parts, alternating with the buttermilk, starting and ending with flour. Make sure each addition is incorporated before adding the next, but don't over-beat it at the end. Spread the batter in the prepared pan and smooth the top.
Bake until the top is puffed and golden brown and a tester inserted in the center comes out clean, about 35 minutes
Serve warm or at room temperature, with lightly sweetened fruit (I added about a tablespoon of sugar to a pint of sliced strawberries and two sliced nectarines) and whipped cream.