• Preheat the oven to 350 degrees Fahrenheit and line a baking sheet with parchment paper.  Set aside.

For the Streusel:

• Mix together all the streusel ingredients in a medium size mixing bowl with a pastry cutter or a fork until combined.
• Refrigerate while you prepare the cookie dough.

For the Cookies:

• Mix together the butter with the brown sugar and sugar with a hand held mixer or stand up mixer until combined and smooth.
• Add in the cinnamon, egg and vanilla extract until combined.
• Then turn the mixer down to low and add in the flour, cornstarch, baking powder, baking soda and salt until just combined.  Be careful not to over mix the dough.
• Use a large cookie scoop (approximately 3 tablespoons) to scoop the dough into 12 even rounded balls and place them on the baking sheet at least 2 inches apart.
• Make an indention into the center of each cookie ball with your thumb or a small spoon.
• Place approximately 1 tablespoon of the streusel into each of the cookie dough indentions.
• Bake for 10-12 minutes until the edges are set and start to brown slightly.
• Allow the cookies to set for 10 minutes on the baking sheet and then move them to a wire rack to cool completely. Sprinkle any remaining streusel mixture on top of the cookies while they cool before topping with the glaze.  

For the Glaze:

• Whisk all the glaze ingredients together in a small bowl.  Check the consistency of the glaze.  Add more milk if the glaze does not drizzle easily.
• Drizzle the glaze over each of the cookies and then the cookies are ready to serve and enjoy!