3 cups sifted cake flour, spooned in and leveled
1/2 teaspoon salt
1/2 teaspoon baking soda
1 cup (2 sticks) unsalted butter, slightly firm
2 cups superfine sugar
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3 large eggs
3 tablespoons very fresh instant coffee crystals, dissolved in 1 tablespoon boiling water
1 teaspoon pure vanilla extract
1/4 cup Scotch whiskey
1 cup sour cream
Powdered sugar, for dusting
1. Position the rack in the lower third of the oven. Heat the oven to 325 degrees F. Generously butter a 9-inch Bundt pan, dust with flour, then invert it over the kitchen sink and tap firmly to remove the excess flour. Set aside.
2. In a large bowl, thoroughly whisk together the flour, salt, and baking soda. Set aside.
3. Cut the butter into 1-inch pieces and place in the bowl of an electric mixer fitted with the paddle attachment. Mix on medium speed until smooth and lightened in color, about 2 minutes. Add the superfine sugar gradually, 1 to 2 tablespoons at a time, taking 6 to 8 minutes. Add the eggs, one at a time, about 1 minute apart, scraping the side of the bowl as needed. Blend in the dissolved coffee and the vanilla.
4. Reduce the mixer speed to low. Stir the Scotch into the sour cream and add the mixture alternately with the dry ingredients, dividing the flour into three parts and the sour cream mixture into two parts, beginning and ending with the flour. Mix just until blended after each addition. Scrape the side of the bowl and mix for 10 seconds longer.
5. Spoon the batter into the prepared pan, smooth the top with the bottom of a large soupspoon, and bake for 1 hour and 15 to 20 minutes. The cake is done when the top is springy to the touch and a wooden skewer inserted deeply in the center comes out clean.
6. Remove the cake from the oven and let stand on a cooling rack for 20 minutes. Invert the cake onto the rack, gently lift off the pan, and cool the cake completely. When ready to serve, dust with powdered sugar.
Storage: Store under a glass cake dome or covered with aluminum foil for up to 5 days. This cake may be frozen.