To prepare crust, combine the butter, 1/2 cup sugar, and vanilla in a large bowl. Beat at medium speed of a mixer until light and fluffy (about 2 minutes). Lightly spoon flour into dry measuring cups; level with a knife. Add flour and salt to butter mixture, beating at low speed until well-blended.
Preheat oven to 400°.
Pat dough into a 13 x 9-inch baking dish coated with cooking spray, and pierce bottom of dough with a fork. Bake at 400° for 12 minutes or until lightly browned. Cool crust on a wire rack.
To prepare filling, drain mandarin oranges over a large bowl, reserving 1/2 cup juice. Combine juice, 1/4 cup sugar, sour creams, and pudding mix in a large bowl. Stir in the orange segments. Spoon orange mixture over crust, spreading evenly. Top with whipped topping. Chill 1 hour. Garnish with mint, if desired.