Swiss butterhorns filled with nuts and cinnamon, drizzling with delicious frosting! A delightful treat!
Measure flour and salt into a bowl. Cut in butter. Stir in egg yolk and sour cream; mix well. Shape dough into a ball and wrap in waxed paper. Chill at least one hour or overnight. Divide dough into three parts. On lightly floured board, roll each into 12-inch circles, then cut in 12 pie-shaped wedges. Blend sugar, nuts and cinnamon. Sprinkle each wedge with sugar mixture. Starting at wide edge, roll up. Place on greased baking sheet with point tucked underneath. Bake at 375 degrees 20–25 minutes. Remove from oven. Frost while warm.
Blend together sugar, water and vanilla; spread or drizzle on warm butterhorns.