Preheat oven to 325 degrees F.
Lightly butter a 10-inch tube pan, and line the bottom with parchment paper; set aside.
Combine butter and cream cheese in the bowl of an electric mixer fitted with the paddle attachment, and beat on medium speed until smooth. Add the sugar, increase the speed to high, and beat until light and airy, about 5 minutes. Add the eggs, 1 at a time, beating after each addition and scraping down the sides of the bowl with a rubber spatula as needed. Add the vanilla, then the flour and salt all at once. Beat just until incorporated.
Pour the batter into the prepared pan, and shake lightly to even out the top. Bake until cake is golden brown and a cake tester inserted in the cake comes out clean, 1 hour 15 minutes.
Place the pan on a cooling rack, and cool for 20 minutes. Remove cake from pan, and let cool completely. Serve at room temperature.
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