Preheat oven to 350°. In a small bowl, mix sour cream, vanilla paste and vanilla extract until combined. Let stand 10 minutes. Line bottoms of 3 greased 9-in. round baking pans with parchment; grease paper., Sift cake flour, sugar, baking powder and salt together twice into a large bowl. Add butter and canola oil; beat until mixture is crumbly. Add egg whites, 1 at a time, beating well after each addition. Add eggs, 1 at a time, beating well after each addition. Beat in sour cream mixture just until combined. , Transfer batter to prepared pans. Bake until a toothpick inserted in center comes out clean, 30-35 minutes. Cool in pans 10 minutes before removing to wire racks; remove paper. Cool completely. Frost cake as desired.