Preheat your oven to 350°F (175°C).

In a large mixing bowl, combine softened butter, vegetable oil, and brown sugar. Beat until light and fluffy.

Incorporate the egg and vanilla extract into the mixture. Mix on low speed until combined.

Gradually sift in the dry ingredients: cinnamon, baking soda, baking powder, salt, and all-purpose flour. Mix gently.

In a separate bowl, combine softened butter, brown sugar, flour, and cinnamon for the streusel topping.

Portion the cookie dough onto a lined baking sheet, spacing them about 2 inches apart.

Make indents in the center of each cookie dough ball and fill with the streusel mixture.

Bake for 10-12 minutes or until edges are lightly golden.

While baking, whisk together powdered sugar, milk, and vanilla for icing.

Once cooled, drizzle icing over each cookie.