Makes 10 pieces
Sift together the dry ingredients. Cut in butter until mixture is like dry meal.
Combine the beaten egg with the sour cream and stir into first mixture a little at a time.
Turn the moist soft dough onto a lightly floured board. Shape into a roll about ¾ inch thick and cut crosswise into about 10 pieces.
Place on a greased baking sheet and bake in a preheated 450° oven about 20 minutes. When well risen and light brown, remove and cut each piece into 2 pieces. Return rusks to warm oven to dry out.