Position an oven rack in the center, and preheat the oven to 350˚F.
Butter an 8-cup capacity loaf pan measuring 9 x 5 x 3-inches or 10 x 4 1/2 x 3-inches, and dust the pan lightly with flour, tapping out excess.
Cut each stick of cold butter into 6 equal slices and put the butter into the mixer bowl of a stand mixer.
Let stand about 10 minutes until the butter has softened slightly. If you have a digital probe thermometer, insert the tip into the butter. When it registers about 60 degrees, the butter is ready to be beaten.
Meanwhile, put the 5 eggs into a medium bowl and cover them completely with warm tap water for 5 minutes just to take the chill off. Option: Egg yolks also add moistness, so I used 3 large eggs and 4 large egg yolks instead of 5 whole eggs.
Pat the eggs dry and crack them into a 2-cup glass measure with a pouring spout. Add the yolks and beat with a table fork just to combine well.
Beat the butter with the flat beater on medium speed until it is creamy and fluffy, 1 to 2 minutes. Stop occasionally to scrape the butter from the beater and the sides of the bowl. The butter must have a creamy look.
Add 1/4 cup of the sugar and the vanilla and beat on medium-high speed for 30 seconds.
Scrape the bowl and beater.
While beating on medium speed, gradually add the remaining 1 cup sugar in a slow steady stream, taking about 1 minute to do so.
Scrape the bowl and beater again, and beat on medium high speed for 5 minutes. The butter and sugar will creep up the sides of the bowl.
To insure thorough creaming, stop two or three times to scrape the bowl and beater. Keep track of the actual beating time of 5 minutes. At the end of beating the butter/sugar will look fluffy.
Its temperature will be about 68˚F.
Scrape the bowl again. Set the mixer to medium speed and gradually add the beaten eggs in a slow, steady stream, taking about 1 minute. Then beat 1 minute more on medium-high to high speed until fluffy-looking.
Sift together the flour, potato starch, and salt 3 times to combine thoroughly.
On low speed, add the flour mixture in 3 additions alternating with the heavy cream in 2 additions, beginning and ending with the dry ingredients. Mix only until everything is incorporated and the batter is smooth. The batter will be thick.
Scrape the batter into the prepared pan and spread it level. The pan will be about ¾ full.
Bake about 65 to 75 minutes, until the cake is golden brown, domed in the center, and a wooden skewer inserted into the center comes out clean.
Cool the cake in its pan on a wire rack for 20 minutes.
To release the cake from the pan, run a table knife all around the sides of the cake.
Cover the cake with a wire rack and invert. Carefully remove the pan, cover the cake with another rack and invert so that cake is right side up.
Pound cake is at its tenderest right after it has cooled to room temperature, in about 3 hours. I love eating a slice then.
The cake has a fine texture with bubbles of different sizes.
When completely cool, wrap airtight in plastic wrap and leave at room temperature.
To serve, use a serrated knife and cut into thin slices, two to a portion.
If wrapped properly, pound cake will keep well at room temperature for several days.
You can also freeze pound cake. Wrap the cooled cake securely in plastic wrap, then in foil, label and date, and freeze for up to 4 months. Thaw completely—overnight is best—before unwrapping.
Makes 1 loaf cake weighing just over 2 pounds.