Georgia Peaches-and-cream Cake

CRUMB TOPPING
1/2 c Unbleached all-purpose flour
6 tb Light brown sugar
4 tb Unsalted butter; chilled
1/4 ts Cinnamon

–CAKE–
6 tb Sour cream
1/4 ts Baking soda
1 lg Egg
1/3 c Sugar
4 tb Unsalted butter; softened
1 1/2 ts Pure vanilla extract
3/4 c Unbleached all-purpose flour
1/2 ts Baking powder
1/4 ts Salt

PREHEAT OVEN TO 375F 15 minutes before baking, with the rack in the center
of the oven. Butter an 8-inch square baking pan, preferably glass. Cut the
peaches into 1/2-inch slices. Put in a pan with sugar, lemon juice, tapioca
and nutmeg and toss gently. Cook over high heat until syrup begins to
bubble, about 4 minutes. Set aside.

FOR THE TOPPING: Work the flour into the sugar, butter and cinnamon until
the butter is the size of small peas. This can be done with a food
processor or pastry blender. Set aside.

FOR THE CAKE: Stir the sour cream and baking soda together and let stand
while you begin the cake. Cream the egg, sugar and butter in the processor
or with a mixer until it is light and fluffy. Add the vanilla and sour
cream and mix well. Gently fold in the flour, baking powder and salt. In
the processor, do this by pulsing the machine on and off several times.
Spread the warm peaches and their juice in the bottom of the baking pan.
Spoon the batter over the peaches and spread in a thin, even layer with a
rubber spatula. It’s OK if the peaches are not completely covered. Sprinkle
the topping over the batter. Bake until a toothpick inserted into the
center of the cake–not the fruit–comes out clean, 25-to-28 minutes.