Preheat oven to 300°F (150°C).

In the bowl of a stand mixer fitted with the paddle attachment, beat butter and granulated sugar at medium speed until fluffy, 6 to 8 minutes, stopping to scrape sides of bowl. Add eggs, one at a time, beating well after each addition. Beat in vanilla.

In a medium bowl, sift together flour, salt, and baking soda. With mixer on low speed, gradually add flour mixture to butter mixture alternately with cold sour cream, beginning and ending with flour mixture, beating just until combined after each addition.

Spray a 10-cup fluted tube pan with baking spray with flour. Spoon batter into prepared pan. Firmly tap pan on a kitchen towel-lined counter a few times to settle batter.

Bake until a wooden pick inserted near center comes out clean, 1 hour and 5 minutes to 1 hour and 15 minutes, loosely covering with foil to prevent excess browning, if necessary. Let cool in pan for 15 minutes. Invert cake onto a wire rack, and let cool completely. Just before serving, garnish with confectioners’ sugar, if desired. Store in an airtight container for up to 5 days.