Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper.

Cream the softened butter, vegetable oil, and brown sugar until light and fluffy.

Beat in the egg and vanilla extract until fully incorporated.

Whisk together the flour, cinnamon, baking soda, baking powder, and salt in a separate bowl.

Gradually add the dry mixture to the wet ingredients, mixing until just combined.

Combine softened butter, brown sugar, flour, cinnamon, and salt for the streusel topping until crumbly.

Drop generous portions of dough onto the baking sheet, spaced 2 inches apart.

Fill the indent in each dough ball with the streusel topping.

Bake for 10-12 minutes until lightly golden around the edges.

Whisk powdered sugar, milk, and vanilla until smooth, then drizzle over cooled cookies.