Active Time

　　45 min

　　Total Time

　　3 hr

　　While this little square cake may appear modest, its caramel flavor drew everyone in our test kitchens back for seconds and even thirds. Buttermilk lends a subtle tang and tenderizes the yellow cake, but it's the sweet glaze that really makes this dessert special.

　　

Ingredients

Makes 9 servings

　　

For cake

2 cups plus 2 tablespoons sifted cake flour (not self-rising; sift before measuring)

　　1 teaspoon baking powder

　　3/4 teaspoon baking soda

　　1/2 teaspoon salt

　　1 stick unsalted butter, softened

　　1 cup sugar

　　1 teaspoon pure vanilla extract

　　2 large eggs, at room temperature 30 minutes

　　1 cup well-shaken buttermilk

　　

For caramel glaze

1 cup heavy cream

　　1/2 cup packed light brown sugar

　　1 tablespoon light corn syrup

　　1 teaspoon pure vanilla extract

　　Equipment: a candy thermometer

　　

Make cake:

Step 1

Preheat oven to 350°F with rack in middle. Butter an 8-inch square cake pan and line with a square of parchment paper, then butter parchment.

　　

Step 2

Sift together flour, baking powder, baking soda, and salt.

　　

Step 3

Beat butter and sugar in a large bowl with an electric mixer at medium speed until pale and fluffy, then beat in vanilla. Add eggs 1 at a time, beating well after each addition. At low speed, beat in buttermilk until just combined (mixture may look curdled). Add flour mixture in 3 batches, mixing until each addition is just incorporated.

　　

Step 4

Spread batter evenly in cake pan, then rap pan on counter several times to eliminate air bubbles. Bake until golden and a wooden pick inserted in center of cake comes out clean, 35 to 40 minutes. Cool in pan on a rack 10 minutes, then run a knife around edge of pan. Invert onto rack and discard parchment, then cool completely, about 1 hour.

　　

Make glaze:

Step 5

Bring cream, brown sugar, corn syrup, and a pinch of salt to a boil in a 1 1/2-quart heavy saucepan over medium heat, stirring until sugar has dissolved. Boil until glaze registers 210 to 212°F on thermometer, 12 to 14 minutes, then stir in vanilla.

　　

Step 6

Put rack with cake in a shallow baking pan and pour hot glaze over top of cake, allowing it to run down sides. Cool until glaze is set, about 30 minutes.

　　Cooks' note:

　　Cake (before glazing) can be made 1 day ahead and kept in an airtight container at room temperature.