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

In a large mixing bowl, cream together ½ cup of softened butter, ½ cup of vegetable oil, and 1 cup of brown sugar until light and fluffy. Beat in one large egg and 1 teaspoon of vanilla extract until well combined. Mix in 2 ½ cups of all-purpose flour, 2 teaspoons of ground cinnamon, ½ teaspoon of baking soda, ½ teaspoon of baking powder, and ½ teaspoon of salt until smooth.

In a separate bowl, mix ¼ cup of softened butter, ¼ cup of brown sugar, 1/3 to ½ cup of flour, ½ teaspoon of ground cinnamon, and a pinch of salt to form a crumbly texture.

Scoop portions of dough onto the baking sheets, spacing 2 inches apart, and press an indent in each.

Fill each indent generously with the streusel mixture, allowing it to peak above the cookie dough.

Bake for 10-12 minutes until golden brown around the edges and soft in the center.

Cool cookies for about 5 minutes. Whisk together ½ cup of powdered sugar, 1 tablespoon of milk, and a splash of vanilla extract, then drizzle over warm cookies.