Coffee cake cookies are bakery-size cinnamon spiced cookies coated in buttery streusel and drizzled with sweet vanilla icing. They have delightful crispy edges and soft and chewy centers.
STEP 1: Cut the cold butter into small cubes. Then, add the flour, brown sugar, cinnamon and salt to small bowl. Using your fingers, work the butter into the mixture until small clumps begin to form.
STEP 2: Add the whole egg and yolk, one a time, followed by the vanilla extract. Beat for 2 minutes. Then, add in the flour mixture. Mix just until combined.