1 3/4 c. sifted cake flour
1 tsp. baking soda
1/4 tsp. salt, if desired
1 tsp. cinnamon
1/2 tsp. nutmeg
1/8 tsp. ground cloves
Zest of 1 lg. orange
1 c. firmly packed light brown sugar
1 lg. egg
1 tsp. vanilla
1 stick unsalted butter at room temperature, cut into 6 pieces
1 c. buttermilk
Confectioners sugar, if desired

If you use regular flour, remove 2 tablespoons from each cup.

Adjust oven rack to center position and preheat oven to 350 degrees. Butter 9x9x2 baking pan and dust lightly with flour; tap out excess.

Insert metal blade in food processor. Put flour, baking soda, salt, cinnamon, nutmeg, and cloves into work bowl and process for 5 seconds. Transfer to large piece of waxed paper and set aside.

With metal blade in place, put zest and brown sugar into work bowl and process, stopping twice to scrape bowl, until zest is finely chopped, about 2 minutes.

Add egg and vanilla to work bowl and process for 1 minute, stopping once to scrape work bowl. Add butter and process for about 1 minute, stopping once or twice to scrape work bowl; mixture should be smooth and fluffy. With machine running, add buttermilk through feed tube and process for 10 seconds.

Add dry ingredients in circle on top of batter. Pulse rapidly 4 times, scrape work bowl gently, and pulse once more, just until dry ingredients are incorporated. Do NOT overprocess; if necessary, stir with plastic spatula to complete mixing. Batter may not be completely smooth.

Turn batter into pan and tilt gently to level it. Bake until top is well browned and springs back when gently pressed with fingertip and cake pulls slightly away from side of pan, about 30 minutes. Cool in pan for 5 minutes, then turn out onto rack. Remove pan, cover with another rack, and invert again to let cake cool completely right side up. Before serving, sprinkle top lightly with confectioners sugar, if desired.