Coffee Cake Cookies

Preheat the oven to 375 F. Line 2 baking sheets with parchment paper.
Place the butter and sugars in a stand mixer fitted with a paddle attachment. Beat on medium-high speed until light and fluffy, 3 to 4 minutes.
Add egg, yolk and vanilla, mix until smooth on low speed.
Slowly mix in baking powder, soda, salt, cornstarch and flour, being careful not to over mix. I usually stop when I still have some flour remnants around the bowl.
Scoop the dough into 3 tablespoon size balls and place 6 cookies on cookie sheet. Take the backside of the cookie scoop and push to make an indention in each cookie dough ball, or you can use your fingers.
Mix together flour, brown sugar, salt and cinnamon in a small bowl. Add soft butter and mix together with a fork or your fingers until it all comes together. Take a handful of crumb topping and place it in the indention of the cookie dough.
Bake for 9-12 minutes, or until the edges start to turn golden brown. Run a spoon or spatula around the freshly baked cookies to help shape a perfect circle. Allow to cool completely before adding the glaze.
Mix together the glaze. Drizzle over the cooled cookies. Enjoy!