Dissolve yeast and 2 tablespoons sugar in lukewarm milk. Add 3 cups flour and beat well. Cover and set aside to rise in warm place about 1 hour, or till the bubbles on top all burst.
Cream butter and sugar together then add to dough mixture. Add beaten eggs, salt, and cinnamon. Knead lightly. Place in greased bowl, cover, and let rise about 1 1/2 to 2 hours.
Shape to donuts, let rise again then bake.