• Preheat the oven to 350°F.

Cinnamon Dough

• With a hand mixer or stand mixer, blend together the softened butter, oil, and brown sugar until the mixture achieves a smooth consistency.
• Add the egg and vanilla. Mix just until incorporated.
• Add the cinnamon, baking soda, baking powder, salt, and flour and mix until well combined. Set aside.

Streusel

• Add the softened butter, brown sugar, salt, and cinnamon to a bowl. Add ⅓ cup of flour. Start to combine the ingredients, ensuring that the mixture sticks together while also crumbling when you run it through your fingers. Gradually add 1 tablespoon of flour at a time until the desired crumbly texture is achieved. Set aside.

Icing

• In a small bowl, whisk together the powdered sugar, milk, and vanilla until the mixture becomes smooth and runny. Set aside.

Assembly

• Line a cookie sheet with parchment paper. With a large cookie scoop, place a ball of dough onto a baking sheet. Create an indent on the top of the dough using the back of the cookie scoop or your fingers. Then, generously sprinkle a couple of tablespoons of streusel into the created indent on the cookie's surface.
• Bake the cookies for 10-12 minutes at 350°F. Let the cookies cool.
• Once the cookies have cooled slightly, generously drizzle the icing over them.