Measure flour and salt into a large bowl. Cut in butter and combine well. Stir in egg yolk and yogurt. Mix well. Shape dough into 3 balls, wrap in waxed paper and chill for at least 1 hour. Then, on a lightly floured surface, roll each ball into a 12” circle.
Spread Nutella very thinly over entire circle. Using a pizza cutter, cut dough into 16 equal wedges. Ross each wedge, starting at the wide edge. Place on ungreased cookie sheet with pointed tip tucked underneath. Repeat for the other two dough balls. Bake at 375º for 20 minutes or until lightly browned. Cool on racks. Whisk together powdered sugar, water, and almond extract to make a simple icing. Drizzle lightly over cooled butterhorns, just to glaze.
I've grown up eating these delicious treats! Now my 3 children beg for them during DUB. Thanks, Mom!!