Sour Cream Doughnuts

For Doughnuts: Whisk first 5 ingredients in medium bowl to blend; set aside.

Using electric mixer, beat sugar and eggs in large bowl until very thick, about 3 minutes. Beat in orange peel and vanilla. Gradually beat in butter; beat in sour cream.

Gently fold in reserved flour mixture (dough will be slightly sticky).

Cover; set aside 1 hour.

Press out 1/3 of dough on lightly floured surface to 1/2 to 2/3-inch thickness. Using a 2 1/2-inch diameter round cutter, cut out doughnuts. Repeat with remaining dough.

Heat about 1 1/2-inches of oil in a large deep skillet to 365°F to 370°F (185°C).

Fry doughnuts, 3 or 4 at a time, until golden brown, about 1 minute per side. Using slotted spoon, transfer doughnuts to paper towels to drain. Cool doughnuts slightly before glazing.

For Glaze: Combine powdered sugar, vanilla extract and 4 tablespoons cream in a medium bowl; whisk until smooth. Whisk in additional cream, 1 teaspoon at a time, to form a medium-thick glaze.

Spread glaze over tops of doughnuts.