In a mixing bowl, combine all ingredients and mix together thoroughly (in this order), stirring as you add each ingredient:
1 stick softened butter (1/2 cup)
3/4 cup sugar
1 egg
2 extra egg yolks only
1 Tblsp. fresh grated lemon zest
2 Tblsp. fresh lemon juice
1 tsp. vanilla
2 -1/4 cups flour
1 tsp. baking powder
1/2 tsp. cardamom (powder, not whole seeds)
1/4 tsp. salt
(At this point, you could add a cup of finely chopped nuts or 1/4 cup poppy seeds - I chose to leave them plain.)
Divide the dough in half. Form each into a log and place on a lightly greased baking pan, leaving several inches of space between them. (Approx. 10" long X 1/2" high X 2-3" wide)
Brush with lightly beaten egg white and sprinkle lightly with sugar.
Bake for 20-25 minutes, until golden on top. Remove from oven and let cool for 10-15 minutes. Slice into 1/2" slices, lay them flat onto the baking sheet, return to the oven and bake another 10-14 minutes until they're lightly toasted/golden.
