In a stand mixer or using a bowl and a hand mixer cream together the butter, sugar, rosemary, lemon zest and salt until light and fluffy on medium speed for about 2-3 minutes.
Add the lemon juice, flour, almond flour and corn starch and mix on low speed until incorporated.
Divide the dough in half and form into 2 square logs approximately 7” long and 1 ¼” square.
I like to roll the logs to the desired length and then wrap in plastic wrap. I then begin to gently press flat and continue to turn so that you have flattened on 4 sides creating the square shape.
Place in the refrigerator to chill for about 2 hours. When chilled slice the logs 1/4” and place the slices on a parchment lined baking sheets. For longer storage wrap well and place in the freezer.
Bake at 350 degrees for 13-14 minutes or until the edges begin to brown slightly.
Remove from the oven and allow to cool for about 1-2 minutes. Dredge the cookies in the powdered sugar and place on a rack to cook completely.
Store in a air tight container separated by parchment or waxed paper. Before serving you may need to re-dredge in powdered sugar.
Make approximately 50 cookies.